bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrologic projections for Australia: understanding future changes to water availability and extremes
Authors: Bende-Michl Ulrike , Sharples Wendy , Donnelly Chantal , Vogel Elisabeth , Peter Justin , Hope Pandora , Srikanthan Sri , Tuner Margot , Oke Alison , Matic Vjekoslav , Lerat Julien , Roussis Jake , Duong Vic CO , Pipunic Robert
Published: March 2021

Australia's large natural hydro-climatic variability has already seen many changes, such as declining rainfall in the southern part of the country. Understanding these shifts and associated impacts on water availability is an important issue for Australia, as water supply is dependent on the generation of surface water resources. Sustainable future urban and agriculture developments will depend on best available knowledge about the risks and vulnerabilities of future water availability.

To understand those risks and vulnerabilities and to mitigate the impact of a changing climate, Australia's water policy, management and infrastructure decision making needs detailed high-resolution climate and water information. This includes information on multi-decadal timescales from future projections in the context of past climate variabilities. In Australia, currently, hydrologic change information exists in various forms, ranging from multiple regional downscaling efforts, bias-correction methods and different interpretation methods for hydrologic impact assessment – all limiting a national, consistent impact assessment across multiple spatial and temporal scales. These regional downscaling and hydrological impact data collections are either not application-ready or are tailored for specific purposes only, which poses additional barriers to their use across the water and other sectors.

To overcome these barriers, the Bureau of Meteorology is soon to release a seamless national landscape water service known as the Australian Water Outlook (AWO), combining historical data on water availability with forecast products, as well as hydrological impact projections. This system's core is the Australian Landscape Water Balance model (AWRA-L) modelling hydrologic variables consistently across a large range of spatial and temporal scales. The AWRA-L model is underpinned by substantial scientific development including data assimilation approaches for model calibration as well as model evaluation approaches for past and present time scales. Additionally, consistent downscaling and bias-correction approaches are integrated for the hydrologic projections in the operational framework.

This presentation will share an overview of the soon to be released Australian Water Outlook seamless service with an emphasis on the Hydrologic Projections part: the methodology, the user centred-design, as well as the development of guidance material containing confidence statements and uncertainty assessments to help decision makers in understanding the service. The presentation will also provide an overview of the tactics we applied to ensure the applicability of the new service including demonstration cases developed in partnership with users.
REOF analysis of ground water level variation in an Urban hard rock aquifer system
Authors: Vijayan Vineeth , Ramachandran Parthasarathy
Published: March 2021

Strategies for sustainable ground water management are to be planned at regional scale. Urban ground water recharge is complex and dynamic. Various factors contribute to ground water level variation. Understanding the ground water recharge components is essential in planning and management of the water resources in any city. This study attempts to understand the spatiotemporal variations of an urban hard rock aquifer system in Bengaluru, India using REOF analysis and Kriging. Bengaluru meets its needs of water supply from river Cauvery. The water supply utility has an increasing block tariff to control the water demand in the city. But it measures only the use of surface water that is being supplied by the utility. Ground water, being a free resource, bridges the demand supply gap in the city. More than half of the water demand in the city is met through ground water. Hence it is essential to understand the components of ground water level variation in this hard rock aquifer system. Rotated empirical orthogonal function (REOF) analysis of monthly piezometric heads from 153 monitoring wells measured during 2015-2017 is used to identify the primary ground water recharge components. The major components of ground water level variation in the study area was identified as rainfall and pipeline leakage. Ordinary Kriging was used to regionalize the identified significant empirical orthogonal functions.
Will hurricane sedimentation aid southeastern US saltmarsh resiliency in the face of climate change and sea-level rise?
Authors: Staro Alice , FitzGerald Duncan , Hughes Zoe , Hein Christopher , Georgiou Ioannis , King Kendall , Connell Jennifer , Pondell Christina
Published: March 2021

Coastal saltmarshes are an important and highly diverse ecosystem, shielding the mainland from erosion and flooding. Along the US East Coast these valuable wetlands are endangered due to climate change, sea-level rise, and reduced fluvial sediment fluxes. Although hurricanes are commonly an erosional agent, they may be responsible for delivering significant volumes of sediment to the marsh surface, which could aid resiliency by increasing vertical accretion. This study analyzes marsh sediment cores collected during December 2017 within the Georgia Bight, targeting deposits associated with Hurricane Irma, which caused significant wave energy and storm surge along the coast from Florida to South Carolina in September 2017.

We have focused our initial research on samples from Sapelo Island (Georgia), where Hurricane Irma produced maximum wind velocities of 17.5 m/s and a 1.3 m storm surge, inundating the marsh for 14.8 hrs. We find that Irma-related layers are between 2 and 7 cm thick and well-oxidized. These deposits typically consist of laminated mud with low organic content (LOI: 10-25%) and low bulk density (0.3-0.8 g/cm3). On average, Irma event sediment thickness is 4 times the historical average annual accretion, which in Georgia salt marshes is 1.55 mm.

A direct comparison of Irma-affiliated marsh accretion and historical rates is complicated due to differences in consolidation, rooting and vegetation, and the sedimentation history of the marsh. Nonetheless, the storm layer represents a significant addition of sediment to the marsh surface. Thus, future increases in event sedimentation, associated with increased frequency or severity of storms, could help compensate for sea-level rise and lessen the likelihood or extent of marsh loss due to submergence.
Role of tropical cyclones along the monsoon trough in the future changes of the Asian monsoon precipitation by high-resolution models
Authors: Takahashi Hiroshi
Published: March 2021

This study examined the future changes of Asian monsoon precipitation to global warming on the regional scale, focusing on tropical cyclones along the monsoon trough. This is because the Asian monsoon precipitation is closely associated with tropical disturbances. To reproduce convective precipitation and tropical disturbances, this study used outputs of high-resolution climate simulations. First, two sets of approximately 30-yr simulations under present-day (control) and warmer climate conditions (global warming) were conducted by the 14-km Nonhydrostatic Icosahedral Atmospheric Model (NICAM) with explicitly calculated convection, which were analyzed (Takahashi et al. 2020). Overall, the Asian summer monsoon was well simulated by the model. Precipitation increased as a result of global warming along the monsoon trough, which was zonally elongated across northern India, the Indochina Peninsula, and the western North Pacific Ocean. This increased precipitation was likely due to an increase in precipitable water. The spatial pattern of the increased precipitation was associated with enhanced cyclonic circulations over a large area along the monsoon trough, although it was difficult to determine whether the large-scale monsoon westerly was enhanced. This enhancement can be explained by future changes in tropical disturbance activity, including weak tropical cyclones. In addition to this result, this study will provide the results of future changes in the Asian monsoon precipitation by high-resolution models. 

Takahashi, H. G., Kamizawa, N., Nasuno, T., Yamada, Y., Kodama and, C., Sugimoto, S., & Satoh, M. (2020). Response of the Asian Summer Monsoon Precipitation to Global Warming in a High-Resolution Global Nonhydrostatic Model, Journal of Climate, 33(18), 8147-8164,
A sparsity-based adaptive filtering approach to Shear Wave Splitting
Authors: Mohammadigheymasi Hamzeh , Ebrahimi Mohammad Reza , Silveira Graça , schlaphorst David
Published: March 2021

Shear wave splitting analysis is a frequently used tool to study elastic anisotropy from the lower mantle to the crust. Several methods have been developed to evaluate the splitting parameters, Φ (fast axis) and δt (delay time), including the correlation of wave components, minimization of covariance matrix eigenvalues, and minimizing energy on the transverse component. Despite massive progress in introducing sophisticated methods, still fundamental problems, related mainly to noisy data, interfering phases, length of the analyzed waveform, and stability and reliability of results, remain. This study presents a sparsity-based adaptive filtering method to magnify the SKS waveforms and suppress the unwanted noise and interfering phases. The study is an extension of Jurkevics (1988), computing the semi-minor and semi-minor axis of the polarized motion in the time-frequency domain using a regularized inversion-based approach imposing a sparsity constraint. Afterward, the elliptical particle motion caused by the split shear waves and correspond to high semi-minor amplitude is derived in the time-frequency domain. The information is used to design an adaptive filter in the time domain to amplify the SKS phase and suppress the noise and other phases having non-elliptical polarization. The regularized inversion-based approach enables obtaining a sparse time-frequency semi-minor map while handling noise problems in the time-frequency decomposition. Conducting synthetic simulations, we show that the proposed method increases the signal-to-noise ratio of the SKS phase in radial and transverse components, giving a better estimation of anisotropy parameters in the presence of noise and other interfering phases. Future work involves implementing the processing algorithm on real data recorded in São Tomé and Prı́ncipe, Madeira, and Canary islands. This research contributes to the FCT-funded SHAZAM (Ref. PTDC/CTA-GEO/31475/2017) and SIGHT (Ref. PTDC/CTA-GEF/30264/2017) projects.
Geochemical characteristics and water pollution by Potentially Toxic Elements at the Varatec creek, Baiut mining area, Romania.
Authors: Santanna Diego , Aryampa Ampurire , Jordan Gyozo , Gheorghe Damian , Szabo Csaba
Published: March 2021

This study provides an identification and evaluation of the Potentially Toxic Element (PTE) (Co, Cu, Cd, Pb, Zn, and Ni) sources, speciation, mobility, distribution patterns, enrichment, and relationships along the Varatic Creek and its tributaries in the Baiut Mining Area, Romania. ICP-OES trace element concentrations were measured in collected samples. The geochemical characterization of the Varatec Creek revealed that the water contains high dissolved metals, high sulfate concentrations, and low pH values, dominated by Ca+2 and SO₄2- cation and anion in streamwater.

The calculated median concentrations were much higher than  the average surface water concentrations in Europe (FOREGS) and decreased in the order of Zn(126.2μg.l-1)>>Cu(3.4μg.l-1)>Ni(1.6μg.l-1)=Cd(1.6μg.l-1)>Co(0.5μg.l-1)>Pb(0.3μg.l-1). The relative variability (MAD/median) follow the order Cd(90%)>Co(80%)=Zn(80%)>Cu(60%)=Ni(60%)>Pb(50%). The regional enrichment factor calculated as the Median/FOREGS(European level) follow the order Cd(156)>>Zn(47)>>Cu(3.8)>Pb(3)=Co(3)>Ni(0.9).

Element distribution, geochemical behavior and source, aqueous speciation modeling, and correlation analysis were performed to estimate the metal sorption to Fe-oxyhydroxide, Mn-oxyhydroxide, and sulfates. Detailed data analysis, reaction modelling and geochemical interpretation revealed two distinct groups of PTEs in the studied mining-impacted streamwater: Ni and Co seem to be associated with the geochemical background, while Cd, Pb, Zn, and Cu are originating from mining activities.
Linking exhumation, paleo-relief, and rift formation to magmatic processes in the Western Snake River Plain, Idaho
Authors: Stanley Jessica , Wetzel Kelsey
Published: March 2021

Southwest Idaho has experienced substantial topographic changes over the Cenozoic that are reflections of complex tectonic and mantle processes. The western Snake River Plain (WSRP) in southwest Idaho has been characterized as an intracontinental rift basin but differs markedly in topography and style from other western Cordilleran extensional structures. It also differs in orientation and structural style from the down warped lava plain of the eastern Snake River Plain that follows the path of the Yellowstone hotspot (YHS). Potential magmatic drivers for WSRP formation include the ~12-10 Ma Bruneau-Jarbidge eruptive center of the YHS or the ~17-16 Ma Columbia River Basalt (CRB) large igneous province. To better constrain the timing and style of rifting in the region we sampled granitoid bedrock from Cretaceous and Eocene-aged plutons from the flanks of the WSRP to detail their exhumation history with apatite (U-Th)/He (AHe) thermochronometry. We present new AHe dates from seventeen samples, with cooling dates ranging range from 7 Ma to 55 Ma. The majority of cooling dates for the Cretaceous plutons are Eocene, and the Eocene intrusions yield Miocene dates. The AHe dates provide thermochronological evidence of rapid cooling and exhumation of the Idaho batholith during the Eocene. This supports the presence a high relief landscape in Idaho associated with regional uplift due to Farallon slab rollback and Challis magmatism. We also find evidence for a post-Eocene decrease in relief, seen in the negative slope on date-elevation relationships in the southwest flank of the WSRP. Our AHe dates indicate limited exhumation on the flanks of the WSRP during Miocene rift formation. We interpret this to be evidence of extension dominated by magmatic intrusions and intrabasin faults rather than basin-bounding faults. Miocene AHe dates show rapid exhumation along the Middle Fork Boise River that had begun by ~17 Ma. We take this to indicate focused incision along the river due to base level fall in the WSRP and the timing suggests that CRB activity was responsible for initiation of WSRP formation
Determining OBS clock drift using ambient seismic noise 
Authors: Naranjo David , Parisi Laura , Jousset Philippe , Weemstra Cornelis , Jónsson Sigurjón
Published: March 2021

Accurate timing of seismic records is essential for almost all applications in seismology. Wrong timing of the waveforms may result in incorrect Earth models and/or inaccurate earthquake locations. As such, it may render interpretations of underground processes incorrect. Ocean bottom seismometers (OBSs) experience clock drifts due to their inability to synchronize with a GNSS signal (with the correct reference time), since electromagnetic signals are unable to propagate efficiently in water. As OBSs generally operate in relatively stable ambient temperature, the timing deviation is usually assumed to be linear. Therefore, the time corrections can be estimated through GPS synchronization before deployment and after recovery of the instrument. However, if the instrument has run out of power prior to recovery (i.e., due to the battery being dead at the time of recovery), the timing error at the end of the deployment cannot be determined. In addition, the drift may not be linear, e.g., due to rapid temperature drop while the OBS sinks to the seabed. Here we present an algorithm that recovers the linear clock drift, as well as a potential timing error at the onset.

The algorithm presented in this study exploits seismic interferometry (SI). Specifically, time-lapse (averaged) cross-correlations of ambient seismic noise are computed. As such, virtual-source responses, which are generally dominated by the recorded surface waves, are retrieved. These interferometric responses generate two virtual sources: a causal wave (arriving at a positive time) and an acausal wave (arriving at a negative time). Under favorable conditions, both interferometric responses approach the surface-wave part of the medium's Green's function. Therefore, it is possible to calculate the clock drift for each station by exploiting the time-symmetry between the causal and acausal waves. For this purpose, the clock drift is calculated by measuring the differential arrival times of the causal and acausal waves for a large number of receiver-receiver pairs and computing the drift by carrying-out a least-squares inversion. The methodology described is applied to time-lapse cross-correlations of ambient seismic noise recorded on and around the Reykjanes peninsula, SW Iceland. The stations used for the analysis were deployed in the context of IMAGE (Integrated Methods for Advanced Geothermal Exploration) and consisted of 30 on-land stations and 24 ocean bottom seismometers (OBSs).  The seismic activity was recorded from spring 2014 until August 2015 on an area of around 100 km in diameter (from the tip of the Reykjanes peninsula).
Surface Mass Balance of the Greenland Ice Sheet in the Energy Exascale Earth System Model
Authors: Schneider Adam , Price Stephen , Wolfe Jonathan , Zender Charles
Published: March 2021

Since 1993, nearly 10 percent of the observed rise in global mean sea level can be attributed to the coincident increase in surface mass loss from the Greenland Ice Sheet (GrIS) (Meredith et al., 2019; WCRP, 2018). To determine the GrIS surface mass balance (SMB), defined as the ice sheet’s annual net (surface) mass increase due to snow accumulation minus ablation, a climate model can be coupled to a snowpack model, which enables simulating relevant hydrologic processes including precipitation, phase changes, and runoff. Recent developments within the Energy Exascale Earth System Model (E3SM) include an active ice sheet component. To explore GrIS snowpack conditions relevant to present-day climate, we conduct simulations demonstrating the evolution of SMB and accumulation of snowpack depth, first in E3SM’s land component (ELM). After forcing ELM’s surface condition using 20th century atmospheric reanalysis, we couple ELM to E3SM’s atmosphere component (EAM) and simulate both atmospheric and snowpack conditions over a fixed GrIS geometry. Finally, we activate the MPAS-Albany Land Ice model (MALI), which enables prognostic SMB calculations including elevation-change feedbacks. We find broad agreement in the spatial patterns of GrIS SMB compared to regional climate model (RACMO) and Community Earth System Model (CESM) simulations. We provide insights regarding the use of a statistical downscaling method, which involves using multiple elevation classes with time-varying areal coverages within ELM grid-cells. Within this dynamic system, we can begin investigating elevation feedbacks, where the atmospheric temperature lapse rate allows the SMB to accelerate both positively and negatively in a rapidly changing climate.

References

Meredith, M., M. Sommerkorn, S. Cassotta, C. Derksen, A. Ekaykin, A. Hollowed, G. Kofinas, A. Mackintosh, J. Melbourne-Thomas, M.M.C. Muelbert, G. Ottersen, H. Pritchard, and E.A.G. Schuur, 2019: Polar Regions. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]. In press.

WCRP Global Sea Level Budget Group: Global sea-level budget 1993–present, Earth Syst. Sci. Data, 10, 1551–1590, https://doi.org/10.5194/essd-10-1551-2018, 2018.
Applicability of connectivity concept for disaster management and hazard mitigation
Authors: Singh Manudeo Narayan , Singh Shobhit , Laha Arnab , Mishra Kanchan
Published: March 2021

The concept of geomorphic connectivity is being widely used since last two decades to understand and explain the various earth surface processes and dynamics. Its applicability to understand inter- and cross-scale process-response systems is now well established. In the present work, we have evaluated the applicability of the geomorphic connectivity framework (Singh et al., 2020, ESPL) for managing and mitigating various geological hazards. For an effective hazard mitigation and management planning, we need to know (a) source of hazard, (b) hazard propagation pathways, (c) probable affected areas, and (d) identification of escape routes/pathways. The connectivity concept can be effectively utilised to satisfy aforementioned requirements. For example, sediment and hydrological connectivity can be used to evaluate the potential pathways, identify sources and affected areas, and to assess return periods of fluvial-related hazards such as debris flow and riverine flash floods. Similarly, the potential sites of landslide, stream congestions (and hence, flash flood)- can be identified by evaluating the channel-slope sediment connectivity and longitudinal hydrological connectivity. The concept of landscape connectivity can play a pivotal role in understanding the forest fire probabilities by evaluating the connectivity between various fire-prone patches of forests, fuel, and the spatial positions of fire-breaking landscape patches. Based on connectivity concepts, the potential paths of forest fire propagation can be demarcated in advance and can play a crucial role in forest fire mitigation. Other than identifying the risk-prone zones with respect to various hazards, connectivity concept can also be used to plan evacuation routes as well. Therefore, we propose that the geomorphic connectivity framework can be a robust tool to manage and mitigate various geological hazards.
Geomorphic signatures of the neotectonic activity in Haridwar-Kotdwar region, Northwestern Himalaya, India
Authors: Kralia Abhishek , Thakur Mahesh
Published: March 2021

In this study, we investigate the ongoing crustal deformation in the Haridwar-Kotdwar piedmont zone of the Northwestern Himalaya, India. The Himalayan mountain front has been actively deforming along the Himalayan Frontal Thrust (HFT) which marks the conjunction between the Siwalik hills and the Indo-Gangetic Plains. We report NNE-SSW trending left lateral strike-slip fault towards the west of the study area namely Haridwar Fault (HF) and it offsets the HFT sinistrally by ~ 9 Km. Using the satellite imagery (Cartosat-1 stereo pairs) flat-lying uplifted river terrace have been identified, which is at an elevation of ~80 m from the flood plain of Mitthawali River. Along with uplifted terraces, the HF offsets various structural features, the rivers flowing across it and manifests itself as a series of scarps and slope breaks visible in the satellite imagery. The Khoh River Fault (KRF) trends N-S and offsets HFT dextrally by ~12 Km, this controls the course of the Khoh River and forms a lateral ramp perpendicular to HFT. The KRF manifests itself geomorphically as uplifted terraces at an elevation of ~50 m from the flood plain of the Khoh River which is conspicuous in the DEM and the Cartosat-1 imagery of the area. The Haridwar-Kotdwar piedmont zone has been surrounded in the north by HFT, in the south by Najibabad Fault (NF), towards east by KRF and the western margin has been dissected by HF. The KRF and HF show signatures of neotectonic activity and offsets HFT at two locations forming two ramps in the region. The piedmont zone has been showing signatures of upwarping which causes sudden migration of the rivers flowing into the piedmont zone on a decadal scale, mainly caused by an E-W trending NF. NF is a blind fault and manifests itself geomorphically by series of knee turn bending of the rivers in the study area. The deformation caused by NF has been comprehended using the satellite imageries and Gradient Length Anomalies (GLA). The GLA results show signatures of upliftment in the piedmont zone along the NF. The Haridwar-Kotdwar piedmont zone is surrounded by neotectonically active faults from four sides, making this block a potential seismic hazard in near future.
Numerical modelling of strain localization by anisotropy generation during viscous deformation
Authors: Halter William R. , Macherel Emilie , Duretz Thibault , Schmalholz Stefan M.
Published: March 2021

Localization and softening mechanisms in a deforming lithosphere are important for subduction initiation or the generation of tectonic nappes during orogeny. Many localization mechanisms have been proposed as being important during the viscous, creeping, deformation of the lithosphere, such as thermal softening, grain size reduction, reaction-induced softening or anisotropy development. However, which localization mechanism is the controlling one and under which deformation conditions is still contentious. In this contribution, we focus on strain localization in viscous material due to the generation of anisotropy, for example due to the development of a foliation. We numerically model the generation and evolution of anisotropy during two-dimensional viscous deformation in order to quantify the impact of anisotropy development on strain localization and on the effective softening. We use a pseudo-transient finite difference (PTFD) method for the numerical solution. We calculate the finite strain ellipse during viscous deformation. The aspect ratio of the finite strain ellipse serves as proxy for the magnitude of anisotropy, which determines the ratio of normal to tangential viscosity. To track the orientation of the anisotropy during deformation, we apply the so-called director method. We will present first results of our numerical simulations and discuss their application to natural shear zones.
Numerical simulation of water film edge dynamics
Authors: Zotova Anna , Troitskaya Yuliya , Kandaurov Alexander , Sergeev Daniil
Published: March 2021

Fundamental contribution to the formation of sea spray under strong winds is provided by the bag-breakup phenomenon - rupture of film in the form of parachute [1]. Breaking of water film into droplets is caused, among other factors, by processes occurring on the free edge of the film moving under action of surface tension forces. The study of these processes will help to understand how characteristics of the film and the drops appearing after its rupture are related.

Using the Basilisk software package with Volume of Fluid advection scheme for interfacial flows, numerical simulation of three-dimensional water film placed in domain filled with air was carried out. The water film was placed into domain filled with air. One of the edges of the film is free, and the second is fixed on the left boundary of the domain; along the third coordinate, the boundary conditions are periodic. At the initial moment of time, the film is defined by a sheet with variable thickness - the upper boundary has the form of a cosine. The change in the shape of the film over time was recorded. It is revealed that the inhomogeneity of the film thickness leads to the appearance of a significant curvature of the edge of the film as it moves under the action of surface tension forces.

This work was supported by the RFBR grants (20-05-00322, 21-55-50005, 21-55-52005) and RSF grant 19-17-00209.

[1] Troitskaya, Y. et al. Bag-breakup fragmentation as the dominant mechanism of sea-spray production in high winds. Sci. Rep. 7, 1614 (2017).
Detection of a marine to terrestrial transition in lake sediment from Baffin Island, Arctic Canada, using sedimentary DNA
Authors: Power Matthew , Crump Sarah , Miller Gifford , Bunce Michael , Allentoft Morten
Published: March 2021

The recent development and refinement of the molecular toolkit to detect ancient DNA in sediment samples (sedaDNA) has allowed the high-resolution reconstruction of ancient ecological communities dating back thousands of years. Specifically, DNA from lake sediment has been used to derive continuous records of ecological community changes through variable paleoenvironmental conditions. These paleoecological reconstructions can be an important tool for understanding how ecosystems may respond to current and future warming, but reliable methods for taxonomic detection are needed in order make optimal use of these bioarchives. In this study, metabarcoding assays targeting mammal, bird, and marine fauna have been carried out across a sediment core collected from Lake Qaupat, Baffin Island, Arctic Canada. While Lake Qaupat is currently ~30 m above sea level, it is located below the local marine limit related to isostatic adjustment after deglaciation. Consequently, initial sediment accumulation is in a marine environment, Combined results from the DNA assays indicate a transitional period over which marine-based fauna are systematically replaced by more terrestrial-based fauna. This transition occurs at a predicted age of 7.4 ± 0.2 ka. This research builds on previous studies to develop Baffin Island paleorecords in an effort to inform future changes to the Arctic system in the context of a rapidly warming world. Ultimately these data will be useful in better informing climate models and how taxa may move, adapt or be extirpated from arctic regions[GHM1] [SC2] .[SC3] 
Sub-seasonal streamflow predictions by combining numerical weather models and re-analysis data in alpine catchments
Authors: Zaramella Mattia , Shtrestha Susen , Callegari Mattia , Crespi Alice , Greifeneder Felix , Borga Marco
Published: March 2021

The European Center for Medium-Range Weather Forecasts (ECMWF) has presented in 2017 its latest seasonal forecasting system, SEAS5, available at 1° spatial resolution and daily timestep. More recently, in 2019, the ERA5 reanalysis dataset was released, replacing ERA Interim in providing climatic variables at a finer spatial and temporal resolution (30 km and hourly respectively). The use of such numerical weather predictions and re-analysis data has increased following the need for skills in planning water resources and preventing hydrogeological risk, as demanded by policy makers, energy stakeholders and public authorities. In this work, we apply at a sub-seasonal timescale the ECMWF-SEAS5 hindcast dataset to assess its prediction skills in the upper Adige river basin in the Eastern Italian Alps. The classical Extended Streamflow Prediction (ESP) framework was designated as a benchmark to assess ECMWF scores over the reference, a model simulation calibrated and validated on the runoff observed from 16 sub-basins and size spanning from 50 to 6900 km2. Before application, ECMWF was downscaled and adjusted to the ERA5 re-analysis data by means of a Quantile Mapping (QM) technique. The analysis was conducted over 23 hindcast years from 1993 to 2016 exploiting the semi-distributed basin-scale hydrological model (ICHYMOD). We showed that the sub seasonal QPF-based forecasts have advantages over the ESP, although, generally their skill deteriorates in lead times after day 15. Moreover, ECMWF predictions better perform during early-spring snowmelt and late summer. During late spring and early summer, the forecast skills of the two frameworks vary from basin to basin depending on specific features and lead times.  
Femtosecond Laser Pulses Propagation in the inhomogeneous Gas Media
Authors: Cidorkina Katsiaryna , Dorozhko Natalia , Svetashev Alexander , Turishev Leonid
Published: March 2021

The present study is devoted to the numerical simulation and analysis of the high-intensity femtosecond LIDAR pulses propagation in the air with a special emphasis on the stimulated Raman scattering (SRS) and the stimulated Raman self-mode (SRSM) processes in optically inhomogeneous gas media.

Numerical models have been developed on the basis of a semi-classical energetic and wave theory, including a set of wave and material equations which allow simulating the gas mixtures, regular or stochastic density inhomogeneity and aerosol particles impact on the femtosecond laser pulse shape and spectrum.

The propagation of laser pulses (λ = 400, 800 nm; τ = 1 ÷ 30 fs) with positive or negative chirp was numerically investigated in pure gases: H2, N2, O2 and their typical atmospherically mixtures.   

The media density or composition (aerosol) inhomogeneity was simulated depending on the ratio between the path length (D), the size of the inhomogeneity (l) and the mean wavelength of pulse spectrum (λ). For D >> l the inhomogeneity impact was considered as a stochastic, while in the case of D < l the inhomogeneity was simulated having a constant gradient along the pulse track.      

For vertical sounding tracks the real atmospheric air density profiles were used.

Aerosol density and size fluctuations were estimated as 5÷30% to the mean value.

In model testing regime the SRS and SRMS modes of the femtosecond laser pulse propagation for tracks of up to 100 m have been calculated for investigating the dynamics of the pulse shape, spectrum and energy change under different initial conditions.

The SRMS mode for 10, 14 and 20 fs laser pulses with energy areas of 3π, 2π, π, π/100 was numerically investigated in different gas and aerosol compositions for tracks of βz = 0.5 ÷ 20, where z is the space coordinate and β – the inverse value of Raman self-scattering defined by the media. 

The results obtained show that the dynamics of pulse propagation in SRMS mode is nonlinear in the pulse shape and spectrum. Moreover, the SRMS mode having a resonance character for 2π-pulses may be misaligned as well as modulated by the inhomogeneity of the medium.
Rapid formation of an ice doline on Amery Ice Shelf, East Antarctica
Authors: Warner Roland , Fricker Helen , Adusumilli Susheel , Arndt Philipp , Kingslake Jonathan , Spergel Julian
Published: March 2021

Surface meltwater accumulating on Antarctica’s floating ice shelves can drive fractures through to the ocean and potentially cause their collapse, leading to enhanced ice discharge from the continent. Surface melting in Antarctica is predicted to increase significantly during coming decades, but the implications for ice shelf stability are unknown. We are still learning how meltwater forms, flows and alters the surface, and that rapid water-driven changes are not limited to summer. The southern Amery Ice Shelf in East Antarctica already has an extensive surface meltwater system and provides us with an opportunity to study melt processes in detail. We present high-resolution satellite data (imagery, ICESat-2 altimetry and elevation models from WorldView stereo-photogrammetry) revealing an abrupt change extending across ~60 km2 of the ice shelf surface in June 2019 (midwinter). We interpret this as drainage of an englacial lake through to the ocean below in less than three days. This left an uneven depression in the ice shelf surface, 11 km2 in area and as much as 80 m deep, with a bed of fractured ice: an “ice doline”. The englacial lake had lain beneath the perennially ice-covered portion of a 20 km2 meltwater lake. The reduced mass loading on the floating ice shelf after the drainage event resulted in flexure, with uplift of up to 36 m around the former lake. Applying an elastic flexural model to the uplift profiles suggests the loss of 0.75 km3 of water to the ocean. In summer 2020, we observed meltwater accumulating in a new lake basin created by the flexure. ICESat-2 observations profiled a new narrow meltwater channel (20 m wide and 3 m deep), rapidly incised inside the doline as meltwater spilled over from the new lake and started refilling the depression. This study demonstrates how high-resolution geodetic measurements from ICESat-2 and WorldView can explore critical fine-scale ice shelf processes. The insights gained will greatly improve our ability to model these processes, ultimately improving the accuracy of our projections.
A comparative assessment of HEC-HMS and VIC hydrological models for simulating hydrological processes in Cauvery River Basin, India
Authors: Reghunath Gowri , Mujumdar Pradeep
Published: March 2021

The hydrological cycle is governed by a number of complex processes which occur at different spatial and temporal scales. Hydrological modelling plays an integral role in enhancing the understanding of hydrological behaviour and process complexities at a range of scales. Different hydrological models have various strengths in the representation of hydrological processes. The performance and applicability of each hydrological model can differ between catchments due to several catchment characteristics and dominant hydrological processes. With a wide variety of model structures, it is important to evaluate how different hydrological models capture the process dynamics in various catchments. This study aims at a comprehensive evaluation of the performance of two widely used hydrological models, namely, the HEC-Hydrologic Modeling System (HEC-HMS) and the Variable Infiltration Capacity (VIC) model, in simulating various water balance components in the sub-catchments of the Cauvery River Basin which is a major river basin in Peninsular India. The basin is characterized by extensive regional variability in land use patterns, water availability, and water demands. The chosen models differ in their model structure complexities, methods adopted for simulation of water balance components, and the representation of geographical information, meteorological and physiographical inputs. The models are calibrated with respect to the observed streamflow at various gauge locations, and the simulated water balance components such as evapotranspiration and baseflow are assessed at annual and seasonal time scales. Also, the impact of the representation of the spatial distribution of input variables and model parameters (lumped versus distributed) are evaluated among the models. This work provides valuable insights into the applicability of various hydrological models in simulating hydrological processes in catchments with high regional complexities. Also, this work aids in the identification of effective models and model parameters which can be useful for hydrological data transfers between catchments as well as predictions in ungauged basins.
Observing solar wind turbulence in the corona with ground-based radio telescopes
Authors: Strauss Du Toit , Botha Gert , Chibueze James , Kontar Eduard , Engelbrecht Eugene , Lotz Stefan , Wicks Robert , Krupar Vratislav , Bale Stuart , Maharaj Shimul , Jeffrey Natasha , Nel Amore , Steyn Ruhann , van den Berg Jabus
Published: March 2021

When point-like galactic and extragalactic radio sources are observed through the solar corona by ground-based radio telescopes, plasma density fluctuations in the turbulent solar wind scatter these photons, leading to an observed broadening and/or elongation of such sources. By observing this broadening for several sources, over several days, we can get information about e.g. the wavenumber and radial dependence of solar wind density fluctuations at very small scales (~30m - 8km) inside the Alfven radius, thereby capturing details of the turbulence dissipation range. Here, we present very initial results of such a study with the MeerKAT radio telescope in South Africa (being, of course, a precursor to the much larger Square Kilometer Array, SKA), discuss the preliminary results, and compare these with theoretical estimates and previous observations.
Image stereoscopic models for the advanced analysis of landslide deformation and thickness
Authors: Desrues Mathilde , Toussaint Renaud , Malet Jean-Philippe
Published: March 2021

The analysis of surface displacement and velocity fields from time series of terrestrial optical images is a useful tool for monitoring gravitational instabilities. It allows to define the state of instability of the slope, its evolution in time, its spatial coverage and to identify if the movement is progressing. Other types of information can also be extracted from landslide surface velocity fields such as the tangential and normal deformation or the strain fields that highlight areas of compression/extension (Travelletti et al., 2014) that can even allow to assess the mechanical properties of the moving mass (Baum et al., 1998). However, applying such advanced approaches necessitates to be able to compute the 3D displacements and deconvolute the normal and tangential displacements.

Landslide ground motion can be measured by various geodetic techniques either in-situ and point-based, or remote and giving access to spatially distributed information. In this study, we privileged a low-cost remote sensing method based on the use of a Single Lens Reflex (SLR) cameras. We acquired data at high frequency (i.e., time-lapse photography) from two fixed cameras at the Montgombert landslide.

The velocity fields were extracted from a time series of 13 images by applying the TSM (Tracing Surface Motion; Desrues et al. 2019) code. To detect tangential and normal displacements, we developed a methodology to construct the 3D displacements directly from the correlation results from the pairwise combination of the two monoscopic velocity fields, and further conducted a deformation analysis.

To estimate the thickness of the moving mass from the 3D displacements derived from the stereoscopic optical images, we propose a methodology based on the law of mass conservation (i.e., displacement incompressible) by invoking the rheology of the material involved (Booth et al., 2013). In order to take into account, in this model, a more complex slip geometry, we introduced a disbonding parameter that marks the presence of a dislocation area at the top limit of the moving mass which traduces a non-zero velocity at the sliding surface.

We present the methodology of reconstruction of the 3D displacements with a stereoscopic approach and of estimation of the landslide thickness by applying them to the Montgombert use case (Savoie, French Alps). The calculated displacement fields are consistent with in-situ data and the estimated depths, suggesting a shallow sliding, are consistent with geotechnical information.
On the syn-orogenic basins of the Alps-Apennines tectonic system in NW Italy
Authors: Piana Fabrizio , d'Atri Anna , Irace Andrea
Published: March 2021

The Alps and the westernmost part of Apennines physically join in NW Italy (Piemonte), where the Apennine thrusts interfered, since Late Oligocene, with both the inner boundary faults of the uplifting Alps axial belt and the outer fronts of the Alpine antithetic retrobelt (the Southern Alps). As the two orogenic belts had been intergrowing since the late Oligocene, coeval syn-orogenic basins developed on both, either as separate depocenters or, more frequently, to form a continuous sedimentary domain, strongly controlled by the tectonic evolution of the Alps-Apennines orogenic system.  These syn-orogenic basins both recorded the main stages of the Alps (neoAlpine events) and Apennines tectonic evolution, whose evidence (mostly represented by regional-scale unconformities) can be correlated within each basin and across them. Correlations (in terms of sharing common geologic events) can be found also with the middle Eocene to lower Oligocene basal part of the Alpine foreland basin succession, which extended continuously on the external side of the Western Alps. This contribution will briefly discuss this complex matter in an integrated Alpine-Apennines perspective and in the frame of the post-Eocene evolution of the Western Mediterranean area.
Landslide tsunamis, from origin to hazard, an overview from the SLATE project
Authors: Løvholt Finn , Rauter Matthias , Zengaffinen-Morris Thomas , Harbitz Carl
Published: March 2021

Landslide tsunamis, despite their importance for the overall tsunami hazard, is not as well understood as earthquake tsunamis. Several uncertain factors contribute to the lack of understanding, such as the variability in the source mechanisms, the dynamics of the landslide and the tsunami generation, as well as the temporal probability of occurrence of landslide events. Here, we present an overview of research activities on landslide tsunami analyses in the H2020 ITN-SLATE project. This research originates from two PhD student projects within SLATE, which have so far resulted in at least six publications with several more in the pipeline. In the SLATE project, we show that both translational and rotational dynamic attributes of the landslide are good indicators of the tsunamigenic potential of slumps using the visco-plastic landslide model BingClaw, by correlating the acceleration times mass and also angular momentum with the induced tsunami height. Moreover, we have employed Navier-Stokes simulations to hindcast model experiments of subaerial landslide tsunamis. By using the experience modelling this benchmark to model tsunamis in many other geometrical settings, the Navier-Stokes model is further employed to test generality and discuss several existing parametric relationships from literature so far available only empirically. New 3D formulations for granular landslide dynamics have further been established. Numerical models have also been set up to simulate real cases such as Anak Krakatoa. Finally, a broad parametric study that constrain the landslide dynamics for a landslide probabilistic hazard analysis is undertaken, to show how using past observations can effectively reduce uncertainties related to landslide dynamics. Combining an overview of the study with some highlights, we show how SLATE has contributed to increasing our understanding of landslide tsunamis and their hazard. We also discuss how the outcome of this project provides a platform for further research. This work has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 721403.
Melt pond retrieval based on LinearPolar algorithm using Landsat data
Authors: Qin Yuqing , Su Jie , Wang Mingfeng
Published: March 2021

The formation and distribution of melt ponds also have an important influence on the Arctic climate. It is necessary to obtain more accurate information of melt ponds on Arctic sea ice by remote sensing. Present large-scale melt pond products, especially melt pond fraction (MPF), still need a lot of verification, and it is a good way to use the very high resolution optical satellite remote sensing data to verify the retrieval MPF of low-resolution melt pond results.

Most MPF algorithm such as Markus (Markus, et al., 2003) and PCA (Rosel et al., 2011) relying on fixed melt pond albedo, LinearPolar algorithm (Wang et. al., 2020) considers that the albedo of melt ponds albedo is variable, it has been proved the retrieval results of this algorithm has a high accuracy of the MPF than that of the previous algorithm based on Sentinel-2 data in Wang et al.’s work. In this paper, we applied this algorithm to Landsat 8 data. Meanwhile, Sentinel-2 data as well as SVM and ISODATA method are used as the comparison and verification data. The results show that the MPF obtained from Landsat 8 using LinearPolar algorithm is the much more closer to Sentinel-2 than Markus and PCA algorithms, and the correlation coefficients of the two MPF is as high as 0.95. The overall relative error of LinearPolar algorithm is 53.5% and 46.4% lower than Markus and PCA algorithms, respectively. And in the cases without obvious melt ponds, the relative error is reduced more than that with obvious melt ponds. This is because LinearPolar algorithm can identify 100% dark melt ponds and relatively small-scale melt ponds, and the latter contributes more to MPF retrieval.

The application of LinearPolar algorithm on Landsat can cover a wider range than Sentinel and enhance the verification efficiency. Moreover, because of the longer time series of Landsat data than Sentinel data, the long-term variation trend of sea ice in fixed areas can be monitored.