bluuebunny/crossref_metadata_2025 huggingface dataset:
The Pore-network Modelling of the Infiltration Experiments Performed on Unsaturated Coarse Sands
Authors: Princ Tomáš , Snehota Michal
Published: March 2021

The research focused on the simulation of the previous experiment described by Princ et al. (2020). The relationship between entrapped air content (ω) and the corresponding satiated hydraulic conductivity (K) was investigated for two coarse sands, in the experiment. Additionally the amount and distribution of air bubbles were quantified by X-ray computed tomography.

The pore-network model based on OpenPNM platform (Gostick et al. 2016) was used to attempt simulation of a redistribution of the air bubbles after infiltration. Satiated hydraulic conductivity was determined to obtain the K(ω) relationship. The results from pore-network model were compared with the results from experiments.

Gostick et al. (2016). Computing in Science & Engineering. 18(4), p60-74.

Princ et al. (2020). Water. 12(2), p1-19.
Preliminary results on the slip history of the Pazarcik Segment of the East Anatolian Fault (Turkey): Insights from the integrated analyses of ASTER T-1 and Landsat 8 OLI multi-spectral imagery-based lithological mapping
Authors: Kırkan Erdem , Uçarkuş Gülsen , Zabcı Cengiz
Published: March 2021

Multi-spectral satellite imagery becomes a powerful tool in analyses of the earth’s surface in various aspects, including tectonic studies. There are many worldwide samples of such studies, documenting the distribution of faulting or deformation of lithological units especially in arid, semi-arid regions. The East Anatolian Shear Zone and its most prominent member, the East Anatolian Fault (EAF), is part of such a region, where the modern techniques of remote sensing can provide information on the history of this transform fault system. The EASZ and the EAF, together form the eastern boundary of the Anatolian Block, which in this study, we compare the efficiency of Advanced Space Borne Thermal Emission and Reflection Radiometer (ASTER) and Landsat-8 Operational Land Imager (OLI) images in the discrimination of lithological formations and the Pazarcik Segment of the EAF. First, we used the band combinations of 2/5/1 and 7/3/1, then 4/3-6/2-7/4 and 1/3-1/9-3/9 band ratios were independently selected in order to make an additional evaluation of the lithological discrimination for Landsat 8 OLI and ASTER T1 images, respectively. In the last stage, we used Principal Component Analysis (PCA), which provided a richer colour spectrum than the Band Combination and Band Ratio methods. The preliminary joint-analysis of these three methods allowed us to better understand the basin geometry along this part of the Pazarcik Segment. Accordingly the northern part of the Golbasi basin which hosts the Golbasi Lake, presents a rhomboidal geometry whereas the southern part is divided from the north with a wedge-shaped basin geometry. Towards southwest of the Pazarcik Segment, the Kisik River is left-laterally offset about ~4.8 km which is detectable on the band ratio images. Most critically, the image analysis highlight a geological offset along the Pazarcik Fault Segment at the Golbasi Lake side of the Hoya Formation. A left-lateral cumulative offset of ~11 km is measured along the displaced Hoya formation favouring the hypotheses of either a diachronic origin for the northern and eastern tectonic boundaries of Anatolia, among which the northern one highly exceeds the eastern boundary in terms of total slip, hence the age, or a wider shear zone where the total strain has been shared among parallel/sub-parallel segments.
A new release of the SURE database of earthquake surface ruptures suited to Fault Displacement Hazard Analysis
Authors: Baize Stéphane , Blumetti Anna Maria , Boncio Paolo , Cinti Francesca Romana , Civico Riccardo , Guerrieri Luca , Nurminen Fiia
Published: March 2021

Fault displacement hazard assessment is based on empirical relationships derived from data of historical surface rupturing earthquakes. This approach is used for land use planning, sizing of lifelines or major sensitive infrastructures located in the proximity of active faults. These relationships provide the probability of occurrence of surface rupture and predict the amount of displacement, both for the main ruptures (principal) and for distributed ones appearing beyond.

Following the first version of the global database SURE 1.0 (Baize et al., 2019), we are continuing the effort to compile observations from well-documented historical and recent surface faulting events in order to feed and improve empirical relationships. The new SURE2.0 global database consolidates the previous version SURE 1.0 data, rejecting some poorly constrained cases, reviewing some cases already in, and adding well-documented new ones (e.g. Ridgecrest sequence, USA, 2019). In total, the SURE 2.0 database has 46 earthquakes, including 15 normal fault cases, 16 reverse fault cases and 15 strike-slip cases from 1872 to 2019. The magnitude range is from M4.9 to 7.9, with ruptures from 5 to 300 km long.

SURE 2.0 provides the geometric location and attribute information of rupture segments in a GIS environment and a spreadsheet reports the amplitude and characteristics of deformation, including data sources and its eventual geometric refinement during analysis. In this new version, we completed an essential task to derive attenuation relationships, by classifying each rupture segment and each slip measurement point, using a ranking scheme based on the pattern and amplitude of the observed rupture traces, and considering the structural context and the long-term geomorphology. This distinguishes the principal rupture (class 1), which is the main surface expression of the source of the earthquake. Typically, in the siting study, this class is assigned to the identified active fault. Class 2 features (distributed ruptures) are characterized by shorter lengths and smaller displacements that appear randomly close and around the main rupture. We introduced the distributed main fracture category (class 1.5), which corresponds to the relatively long minor fractures recognized on cumulative structures secondary to the main fault. Class 3 represents triggered slip evidences on remote active faults, clearly not connected with the earthquake causative fault (sympathetic ruptures).

As was done with reverse fault cases (Nurminen et al., 2020), this new SURE 2.0 version will be used to derive probabilities associated with the rupture distribution  during any type of earthquake.
Marine extreme events in high-resolution coupled model simulations
Authors: Eirund Gesa , Münnich Matthias , Leclair Matthieu , Gruber Nicolas
Published: March 2021

Air-sea interactions have been found to substantially affect and drive marine extreme events. Such extreme events comprise, among others, highly anomalous conditions in ocean temperature, pH, and oxygen content - all of which are crucial parameters directly impacting marine ecosystem. Nevertheless, our understanding of the role of such events in the marine environment remains limited. In addition, the extent to which the interplay between atmospheric and oceanic forcings impacts the spatial and temporal scales of extreme events and affects the marine ecosystem and ocean biogeochemistry remains largely unknown.

 

Given these complex interactions between the atmosphere, the ocean, and marine biogeochemistry, we developed a coupled regional high-resolution Earth System Model (ROMSOC). ROMSOC comprises the latest officially released GPU-accelerated Consortium for Small-Scale Modeling (COSMO) version as the atmospheric model, coupled to the Regional Oceanic Modeling System (ROMS). ROMS in turn includes the Biogeochemical Elemental Cycling (BEC) model that describes the functioning of the lower trophic ecosystem in the ocean and the associated biogeochemical cycle. Our current model setup includes thermodynamical coupling and will be extended further to include mechanical coupling between the atmosphere and the ocean. Here, we present first simulations of our coupled model system for the California Current System (CalCS) at the US west coast at kilometer-scale resolution. We will test the hypothesis if the strong mesoscale coupling of the atmosphere and the ocean as represented in our model impacts the spatial and temporal scales of marine heatwaves and can potentially act to shorten their duration.
A study of decadal Land use-land cover change in Dehradun city.
Authors: Singh Gayatri
Published: March 2021

The present study is to quantify the spatial-temporal pattern of the Land Use/ Land Cover Change (LULCC) during a decade (i.e., 2010 to 2020) in the Dehradun city which is situated in the foothills of the Himalaya, using Landsat data. The study helps in identifying the major bio-physical factors governing LULCC through modern geospatial techniques. Change detection shows that the study area experienced an increase in its urban area from 2010 to 2020 and a comparatively decrease in cropland and forest area. This was due to an increase in its urban population, rapid increase in industrialization and tourism during the same period. The change detection analysis further shows that 2010-2020, associated with change in croplands, change in built-up, forest lands, change in water-bodies, water levels, and rainfall. With comparison of above results and collected socio-economic data in this region, the impact of changing land use & bio-physical/ economic factors on agricultural profitability were analyzed. The result of this study could thus lead to a detailed and lucid spatiotemporal assessment of the major bio-physical factors. It is expected that the study will help in facilitating better policy making and infrastructure development for industries and urbanization.
Investigation of atmospheric aerosols over semi-urban and urban areas in Eastern Indo-Gangetic Plain: seasonal variability and source apportionment using PMF
Authors: Dubey Kanishtha , Verma Shubha
Published: March 2021

The study investigates the chemical composition and source of aerosol origin at a semi-urban (Kharagpur–Kgp) and urban (Kolkata–Kol) region during the period February 2015 to January 2016 and September 2010 to August 2011 respectively. Major water-soluble inorganic aerosols (WSII) were determined using Ion chromatography and carbonaceous aerosols (CA) using OC–EC analyser. A multivariate factor analysis Positive Matrix Factorization (PMF) was used in resolving source of aerosols at the study locations. Seasonal analysis of WSII at Kgp and Kol indicated relative dominance of calcium at both the places followed by sodium, chloride, and magnesium ions. Non-sea salt potassium (nss–K+), a biomass burning tracer was found higher at Kol than at Kgp. Sum of secondary aerosols sulphate (SO42-), nitrate (NO3-) and ammonium (NH4+) was higher at Kol than Kgp with relative concentration of SO42- being higher than NO3- at Kgp which was vice-versa at Kol. Examination of carbonaceous aerosols showed three times higher concentration of organic carbon (OC) than elemental carbon (EC) with monthly mean of OC/EC ratio > 2, indicating likely formation of secondary organic carbon formation. Seasonal influence of biomass burning inferred from nss–K+ (OC/EC) ratio relationship indicated dissimilarity in seasonality of biomass burning at Kgp (Kol). PMF resolved sources for Kgp constituted of secondary aerosol emissions, biomass burning, fugitive dust, marine aerosols, crustal dust and emissions from brick kilns while for Kol factors constituted of burning of waste, resuspended paved road dust, coal combustion, sea spray aerosols, vehicular emissions and biomass burning.
Assessment of nominal data requirements for robust estimation of fractional snow cover in alpine-forested terrain
Authors: Wisniewski Elzbieta , Wisniewski Wit
Published: March 2021

The presented research examines what minimum combination of input variables are required to obtain state-of-the-art fractional snow cover (FSC) estimates for heterogeneous alpine-forested terrains. Currently, one of the most accurate FSC estimators for alpine regions is based on training an Artificial Neural Network (ANN) that can deconvolve the relationships among numerous compounded and possibly non-linear bio-geophysical relations encountered in alpine terrain. Under the assumption that the ANN optimally extracts available information from its input data, we can exploit the ANN as a tool to assess the contributions toward FSC estimation of each of the data sources, and combinations thereof. By assessing the quality of the modeled FSC estimates versus ground equivalent data, suitable combinations of input variables can be identified. High spatial resolution IKONOS images are used to estimate snow cover for ANN training and validation, and also for error assessment of the ANN FSC results. Input variables are initially chosen representing information already incorporated into leading snow cover estimators (ex. two multispectral bands for NDSI, etc.). Additional variables such as topographic slope, aspect, and shadow distribution are evaluated to observe the ANN as it accounts for illumination incidence and directional reflectance of surfaces affecting the viewed radiance in complex terrain. Snow usually covers vegetation and underlying geology partially, therefore the ANN also has to resolve spectral mixtures of unobscured surfaces surrounded by snow. Multispectral imagery if therefore acquired in the fall prior to the first snow of the season and are included in the ANN analyses for assessing the baseline reflectance values of the environment that later become modified by the snow. In this study, nine representative scenarios of input data are selected to analyze the FSC performance. Numerous selections of input data combinations produced good results attesting to the powerful ability of ANNs to extract information and utilize redundancy. The best ANN FSC model performance was achieved when all 15 pre-selected inputs were used. The need for non-linear modeling to estimate FSC was verified by forcing the ANN to behave linearly. The linear ANN model exhibited profoundly decreased FSC performance, indicating that non-linear processing more optimally estimates FSC in alpine-forested environments.
Sensitivity of the CFFDRS Fire Weather Index parameters for Indian weather conditions
Authors: Barik Anasuya , Baidya Roy Somnath
Published: March 2021

The Canadian Forest Fire Danger Rating System (CFFDRS) is used to assess and predict the fire behavior in various forest ecosystems all over the world. The Fire Weather Index (FWI) module of the CFFDRS models the relationship between meteorology and forest fires. It was observed in our earlier study that the values of the FWI and its related parameters were considerably different from the other countries that use the model for their operational fire weather simulation. In this study we evaluate the model performance over Indian climate for a period of 10 years 1996-2005 under various weather scenarios. The daily meteorological data from ECMWF’s ERA5 reanalysis has been used as inputs to the fire model and the active fire data from MODIS Terra and Aqua satellites over the study period has been used to evaluate the capability of model to simulate fire danger. As India has many different climatic zones, we evaluated the behavior fire model parameters over 5 forest zones namely Himalayan, Deciduous, Western Ghats, Thorn forests and North Eastern forests based on the Roy et al. 2016 Land Use Land Cover data and Koppen climatic zones.  The analysis was narrowed down over only the forest areas of the zones so as to remove any chances of including the non-forest fires detected by the satellite. Results show that the FWI shows a strong correlation with forest fires if the model is correctly spun up and appropriately calibrated. A spin up time of minimum 60 days was found to be appropriate for stabilization of FWI components like Duff Moisture Code (DMC) and Drought Code (DC). Sensitivity studies showed that temperature and relative humidity are the key controlling factors of forest fires over India and that the parameters depict high interannual seasonality due to relatively lower values during the Indian monsoon season.

This study is one of the first attempts to use fire models to simulate fire behavior over India. It can serve as a launchpad for further work on fire hazard prediction and effects of climate change on fire hazard in India.
Martian crustal magnetic fields: influences on the ionosphere
Authors: Andrews David , Andersson Laila , Ergun Robert , Eriksson Anders , Pilinski Marcin , Stergiopoulou Katerina
Published: March 2021

Recent Mars Express and MAVEN observations have shown the extent to
which Mars's crustal fields, though weak in absolute magnitude,
nevertheless exert significant control over the structure of the ionosphere
over a range of altitudes. However, quantifying this control remains
challenging given the generally dynamic nature of the Mars solar wind
interaction, and the therefore naturally varying densities and temperatures
of the upper ionosphere in particular. In this study we examine MAVEN
Langmuir Probe and Waves data, and show for the first time a very clear
correspondence between the structure of the crustal fields and both the
measured electron temperatures and densities. Electron temperatures are
shown to be systematically lower in regions of strong crustal fields over a
wide altitude range. We speculate on the origins of this deviation.
The influence of thinning and prescribed burning on future forest fires under different climate scenarios
Authors: Gérard Florence , Rabin Sam , Arneth Almut
Published: March 2021

Forest fires in some regions have intensified over recent decades due to climate change. This trend threatens ecosystems (habitat and biodiversity loss), human health (particulate-matter pollution, smoke), property (burned urban areas, burned forestry yields, monetary loss), and potentially climate mitigation goals (rising carbon dioxide levels, possibly decreased land carbon sink).

Here, we investigate whether forest management can reduce future impacts of forest fire and help to control fire regimes in the future. We are using the process-based dynamic global vegetation model LPJ-GUESS with the fire module SIMFIRE-BLAZE to explore this question. The analyzed treatments compare a non-managed stand with stands receiving thinning, prescribed burning, or both. We focus on two regions: The Iberian Peninsula (due to its long history of burning) and Eastern Europe (which may become more fire-prone in the future). Results are compared between CMIP6 scenarios of low-intensity vs. high-intensity climate change (RCPs 2.6 and 8.5, respectively).

The results show that prescribed fire raises the amount of burned area but possibly not the property risk because fire line intensities are mitigated; thinning can reduce the amount of prescribed fire required. Thinning reduces fire emissions whereas prescribed burning is the other way around, which could contribute to health and climate risks caused by particulate-matter-pollution. Managements do not seem to have effects on the carbon balance according to end of the century carbon pools, which implies that they do not actively help achieve climate mitigation goals.
Initiating FAIR geothermal data in Indonesia
Authors: Irawan Dasapta Erwin
Published: March 2021

One of the main keys to scientific development is data availability. Not only the data is easily discovered and downloaded, there's also needs for the data to be easily reused. Geothermal researchers, research institutions and industries are the three main stakeholders to foster data sharing and data reuse. Very expensive deep well datasets as well as advanced logging datasets are very important not only for exploitation purposes but also for the community involved eg: for regional planning or common environmental analyses. In data sharing, we have four principles of F.A.I.R data. Principle 1 Findable: data uploaded to open repository with proper data documentations and data schema, Principle 2 Accessible: removed access restrictions such as user id and password for easy downloads. In case of data from commercial entities, embargoed data is permitted with a clear embargo duration and data request procedure, Principle 3 Interoperable: all data must be prepared in a manner for straightforward data exchange between platforms, Principle 4 Reusable: all data must be submitted using common conventional file format, preferably text-based file (eg `csv` or `txt`) therefore it can be analyzed using various software and hardware. The fact that geothermal industries are packed with for-profit motivations and capital intensive would give even more reasons to embrace data sharing. It would be a good way for them to share their role in supporting society. The contributions from multiple stakeholders are the most essential part in science development. In the context of the commercial industry, data sharing is a form of corporate social responsibility (CSR). It shouldn't be defined only as giving out funding to support local communities.

Keywords: open data, FAIR data, data sharing 

 
Cloud-based Research Data Infrastructures Integrating In-Situ and Remote Sensing Data
Authors: Jirka Simon , Gräler Benedikt , Rieke Matthes , Autermann Christian
Published: March 2021

For many scientific domains such as hydrology, ocean sciences, geophysics and social sciences, geospatial observations are an important source of information. Scientists conduct extensive measurement campaigns or operate comprehensive monitoring networks to collect data that helps to understand and to model current and past states of complex environment. The variety of data underpinning research stretches from in-situ observations to remote sensing data (e.g., from the European Copernicus programme) and contributes to rapidly increasing large volumes of geospatial data.

However, with the growing amount of available data, new challenges arise. Within our contribution, we will focus on two specific aspects: On the one hand, we will discuss the specific challenges which result from the large volumes of remote sensing data that have become available for answering scientific questions. For this purpose, we will share practical experiences with the use of cloud infrastructures such as the German platform CODE-DE and will discuss concepts that enable data processing close to the data stores. On the other hand, we will look into the question of interoperability in order to facilitate the integration and collaborative use of data from different sources. For this aspect, we will give special consideration to the currently emerging new generation of standards of the Open Geospatial Consortium (OGC) and will discuss how specifications such as the OGC API for Processes can help to provide flexible processing capabilities directly within Cloud-based research data infrastructures.
Sea-level rise driven soil salinization
Authors: Nevermann Hannes , AghaKouchak Amir , Shokri Nima
Published: March 2021

Sea level rise (SLR) is a well-documented aspect of anthropogenic climate change which is primary due to the thermal expansion of seawater and melting of ice caps and glaciers (1). Climate change is expected to exacerbate sea-level rise within the next century, much larger than the observations since the beginning of the recordings. Next to various natural hazards and extreme environmental events such as flooding, the sea level rise poses serious long-standing and possibly irreversible consequences on human timescales in coastal regions. For example, soil salinity is expected to increase near shorelines due to sea level rise. Soil salinization, referring to excess accumulation of salt in soil, is a global problem (2) adversely affecting many environmental and hydrologic processes such as terrestrial ecosystem functioning, water cycle and biodiversity. SLRs shift the saltwater-freshwater boundary in coastal regions which will increase the risk of soil salinization further inland. Considering the growing population living in coastal regions, SLR-driven soil salinization has a severe socio-economic impact posing significant threat to farmlands, wetlands, coastal marshes, forests and other ecosystems. Motivated by the importance of the interaction between SLR, climate change and soil salinization, this study aims to determine how the saltwater-freshwater interface moves under different Representative Concentration Pathways (RCP) scenarios in coastal regions. Groundwater data of coastal wells, Digital Elevation Model’s and satellite images will be used to highlight areas under high risk of soil salinization. The results will enable us to quantify the possible extent of the soil salinization as a result of SLR under different climate scenarios with the associated socio-economic consequences. Such information could support decision making and sustainable resource management under different RCPs.

1. Moftakhari H.M., Salvadori G., AghaKouchak A., Sanders, B.F., Matthew, R.A. (2017). Compounding Effects of Sea Level Rise and Fluvial Flooding. Proc. Nat. Acad. Sci., 114 (37), 9785-9790.

2. Hassani, A., Azapagic, A., Shokri, N. (2020). Predicting Long-term Dynamics of Soil Salinity and Sodicity on a Global Scale. Proc. Nat. Acad. Sci., 117 (52) 33017-33027.
Revising the high frequency response correction of scalar fluxes measured by closed-path eddy covariance systems
Authors: Mammarella Ivan , Peltola Olli , Aslan Toprak , Ibrom Andreas , Nemitz Eiko , Rannik Üllar
Published: March 2021

Eddy covariance (EC) scalar flux loss at high frequency is due to the incapability of the measurement system to detect small-scale variation of atmospheric turbulent signals. This systematic bias is particularly important for closed-path systems, and it is mainly related to inadequate sensor frequency response, sensor separation and the air sampling trough tubes and filters. Here, we investigate the limitations of current approaches, based on measured power spectra (PSA) or cospectra (CSA), to empirically estimated the spectral transfer function of the EC system needed for the frequency response correction of measured fluxes. We performed a systematic analysis by using EC data from a wetland and forest site for a wide range of attenuation levels and signal-to-noise ratio. We proposed a novel approach for PSA that uses simultaneously the noise and the turbulent signals present in the power spectrum, providing robust estimates of spectral transfer function for all conditions. We further theoretically derived a new transfer function to be used in the CSA approach which specifically accounts for the interaction between the low-pass filtering induced phase shift and the high frequency attenuation. We show that current CSA approaches neglect such effect, giving a non-negligible systematic bias to the estimated scalar fluxes from the studied sites. Based on these findings, we recommend that spectral correction methods, implemented in EC data processing algorithms, are revised accordingly.
Ancient sedimentary DNA shows rapid post-glacial colonisation of Iceland followed by relatively stable vegetation until Landnám
Authors: Alsos Inger , Lammers Youri , Kjellman Sofia E , Merkel Marie K. F. , Bender Emma M , Rouillard Alexandra , Erlendsson Egill , Guðmundsdóttir Esther Ruth , Benediktsson Ívar Örn , Farnsworth Wesley R , Brynjólfsson Skafti , Gísladóttir Guðrún , Eddudóttir Sigrún Dögg , Schomacker Anders
Published: March 2021

Understanding patterns of colonisation is important for explaining both the distribution of single species and anticipating how ecosystems may respond to global warming. Insular flora may be especially vulnerable because oceans represent severe dispersal barriers. Here we analyse two lake sediment cores from Iceland for ancient sedimentary DNA to infer patterns of colonisation and Holocene vegetation development. Our cores from lakes Torfdalsvatn and Nykurvatn span the last c. 12,000 cal. yr BP and c. 8600 cal. yr BP, respectively. With near-centennial resolution, we identified a total of 191 plant taxa, with 152 taxa identified in the sedimentary record of Torfdalsvatn and 172 plant taxa in the sedimentary record of Nykurvatn. The terrestrial vegetation at Torfdalsvatn was first dominated by bryophytes, arctic herbs such as Saxifraga spp. and grasses. Around 10,100 cal. yr BP, a massive immigration of new taxa was observed, and shrubs and dwarf shrubs became common whereas aquatic macrophytes became dominant. At Nykurvatn, all dominant taxa occurred already in the earliest samples; shrubs and dwarf shrubs were more abundant at this site than at Torfdalsvatn. There was an overall steep increase both in the local and regional species pool until 8000 cal. yr BP, by which time ¾ of all taxa identified had arrived. In the period 4500-1000 cal. yr BP, a few new taxa of bryophytes, graminoids and forbs are identified. The last millennium, after human settlement of the island (Landnám), is characterised by a sudden disappearance of Juniperus communis, but also reappearance of some high arctic forbs and dwarf shrubs. Notable immigration during the Holocene coincides with periods of dense sea-ice cover, and we hypothesise that this may have acted as a dispersal vector. Thus, although ongoing climate change might provide a suitable habitat in Iceland for a large range of species only found in the neighbouring regions today, the reduction of sea ice may in fact limit the natural colonisation of new plant species.
Climate impact of aircraft-induced cirrus assessed from satellite observations before and during COVID-19
Authors: Quaas Johannes , Gryspeerdt Edward , Vautard Robert , Boucher Olivier
Published: March 2021

Aircraft produce contrail in suitable atmospheric conditions, and these may spread out into cirrus. However, it is unclear how large this effect and its implied radiative forcing is. Here we use the opportunity of the COVID-19 related aircraft traffic reduction in boreal spring 2020 in comparison to the traffic in 2019 to assess satellite data. MODIS retrievals are examined for 2020 vs. the climatology 2011 to 2019. In order to account for weather variability, circulation analogues are defined for each region and day of the Spring 2020 period, and the cirrus coverage and emissivity in springtimes 2011 - 2019 is assessed for comparison to 2020. In conclusion, we find that cirrus are reduced by 9±1.5% in absolute terms. This is consistent with a trend analysis. The implied radiative forcing by aviation-induced cirrus is assessed at 49±28 Wm-2. 
Lena River biogeochemistry resolved by a high frequency monitoring: comparing a wet and a dry year
Authors: Juhls Bennet , Morgenstern Anne , Overduin Pier Paul
Published: March 2021

River biogeochemistry at any location integrates environmental processes over a definable upstream area of the river watershed. Therefore, biogeochemical parameters of river water are powerful indicators of the climate change impact on the entire watershed and smaller parts of it.

The current warming of the Siberian Arctic is changing atmospheric forcing, precipitation, subsurface water storage, and runoff from rivers to the Arctic Ocean. A number of studies predict an increase of organic carbon export by rivers into the Arctic Ocean with further warming of the Arctic. Major potential drivers for this increase are the rise of river discharge and permafrost thaw, which mobilizes organic matter.

Here, we present results of high frequency monitoring program of the Lena River waters in the central part of its delta at the Laptev Sea. For the first time, a number of biogeochemical parameters such as dissolved organic carbon (DOC), coloured dissolved organic matter, electrical conductivity, temperature, and d18O isotopes were measured at an interval of every few days throughout the entire season. Currently, the data set comprises two complete years from the spring 2018 until the spring 2020, which were characterized by extremely high and low summer discharges, respectively. While 2018 to 2019 was the fourth highest on record from 1936 to present, resulting in an annual DOC flux of 6.8 Tg C yr-1, 2019 was the sixth lowest discharge year with a significantly lower DOC flux of 4.5 Tg C yr-1. Endmember analysis using electrical conductivity and d18O isotopes showed that rainwater transported less DOC in 2019 (1.5 Tg C) than in 2018 (2.9 Tg C) although the winter base flow and the snow and ice meltwater transported similar amounts.

The biogeochemical response of the Lena River water provides us with new insights into the catchment processes, including permafrost thaw and potential mobilization of previously frozen organic carbon. Our new monitoring program will serve 1) as a baseline to measure future changes and 2) as a training dataset to project changes under future climate scenarios.
New Imaging Approach for Constraining the Azimuth and Dip of Seismic Anisotropy Using Teleseismic P-wave Delays and its Application to the Western United States
Authors: VanderBeek Brandon , Bodmer Miles , Faccenda Manuele
Published: March 2021

Despite the well-established anisotropic nature of Earth’s upper mantle, the influence of elastic anisotropy on teleseismic P-wave imaging remains largely ignored. Unmodeled anisotropic heterogeneity can lead to substantial isotropic velocity artefacts that may be misinterpreted as compositional and thermal heterogeneities. Here, we present a new parameterization for imaging arbitrarily oriented hexagonal anisotropy using teleseismic P-wave delays. We evaluate our tomography algorithm by reconstructing geodynamic simulations of subduction that include predictions for mantle mineral fabrics. Our synthetic tests demonstrate that accounting for both the dip and azimuth of anisotropy in the inversion is critical to the accurate recovery of both isotropic and anisotropic structure. We then perform anisotropic inversions using data collected across the western United States and offshore Cascadia. Our preliminary models show a clear circular pattern in the azimuth of anisotropy around the southern edge of the Juan de Fuca slab that is remarkably similar to the toroidal flow pattern inferred from SKS splits. We also image dipping anisotropic domains coincident with the descending Juan de Fuca slab. In contrast to prior isotropic tomographic results, the Juan de Fuca slab in our anisotropic model is characterized by more uniform P-wave speeds and is without an obvious slab hole below ~150 km depth. We also find a general decrease in the magnitude of mantle low-velocity zones throughout the model relative to prior studies. These results highlight the sensitivity of teleseismic P-waves to anisotropic structure and the importance of accounting for anisotropic heterogeneity in the imaging of subduction zones.
Soils in silico - solutes, biofilms and structure formation
Authors: Lieu Alice , Zech Simon , Prechtel Alexander , Ray Nadja , Schulz Raphael
Published: March 2021

We assess the complex coupling of biological, chemical and physical processes with the help of a mechanistic modeling approach extending [Rupp 2019] The aim is to study the interplay of relevant mechanisms in silico and consequently gain a model-based understanding of dynamics in soils.
The hybrid discrete-continuum model used explicitly represents the pore structure and allows for dynamic structural organization of the medium at the pore scale. The movement of interacting entities - nutrients, bacteria and possibly charged chemicals - in the fluid is described by means of the diffusion and Nernst-Planck equations with Henry's law at the liquid/gas interfaces. Homogeneous chemical reactions are considered using for instance the mass action law whereas heterogeneous reactions on the solid surface are incorporated via a kinetic Langmuir isotherm. A biomass phase can develop from agglomerations of bacteria and stabilising sticky agents may grow or decay at the solid surfaces. Root cells and an explicit phase of exudate as well as attachment properties of root hairs can be included. In addition to solving the continuous partial differential equations, a discrete cellular automaton method [Ray et al. 2017, Rupp et al 2018, Tang and Valocchi 2013] is used, enabling structural changes in the solid and biomass/mucilage phases at each time step. The partial differential equations are discretised with a local discontinuous Galerkin method which is able to handle discontinuities induced by the evolving geometry. Upscaling techniques enable the incorporation of information from the pore scale into the macroscale.
In this study, we illustrate the ability of the approach to advance the understanding of specific process mechanisms. Microaggregates are the fundamental building blocks of soils and are thus important for soil structure, properties, and functions. Although there has been much research investigating the dynamics, stability, and structure of microaggregates, there is still a substantial lack in quantifying the relationships between the major driving forces (soil fauna, microorganisms, roots, organic and inorganic matter, and physical processes). As an example, we study structure formation of microaggregates as a function of the size and shape of the solid building units taking into account the effect of attraction and repulsion by charges. Biomass development and root exudate can significantly alter the macroscopic soil hydraulic properties. Using the model in hand, this effect can be quantified for different amount and spatial distribution of root exudate with geometries from CT-scans. In the natural environment, microbial communities are highly diverse. We employ the model to investigate the way spatial distribution of organic matter can influence bacterial dynamics.
The different mechanisms of extreme snowfall in the eastern and southern Tibetan Plateau.
Authors: Yao Nan , Liu Lian , Ma Yaoming
Published: March 2021

Snowfall is a key component of the hydrological system of the Tibetan Plateau (TP), and it is also a very sensitive factor to climate change. To understand the mechanism of extreme snowfall in different regions of the TP, we used the 50-year snow depth data from the China Meteorological Administration (CMA) ground observations and the ERA5 reanalysis datasets of European Centre for Medium-Range Weather Forecasts (ECMWF). Results show the threshold of extreme snow in the southern TP is four times greater than that in the eastern region. Sixteen numerical experiments using the weather research and forecasting (WRF) model were conducted to quantify the contribution of water vapor and dynamic conditions to snowfall events. Here are the preliminary results: (1) For the snowfall event caused by local circulation in the eastern TP, the contribution of dynamic conditions is greater than that of moisture conditions. An increase of 10% in the wind field (water vapor) will enhance the snow water equivalent (SWE) by more than 25% (10%). (2) For large-scale circulation, q has a greater effect. But the overall increase in snowfall is smaller than the local circulation. (3) The severe snowfall frequently takes place in the southern TP, where water vapor channel and topographic uplift are significant factors to snowfall. we think the southern simulation will produce interesting results. Our results will provide scientific reference in improving the snowstorm forecasting and disaster prevention and mitigation.
Coordinated observation system for extreme weathers consisting of AWS network with lightning sensor and micro-satellites
Authors: Takahashi Yukihiro , Sato Mitsuteru , Kubota Hisayuki , Ishida Tetsuro , Castro Ellison , Algodon Meryl , Perez Gay , Marciano Joel
Published: March 2021

In order to predict the intensity and location of extreme weathers, such as torrential rainfall by individual thunderstorm or typhoon, we are developing the new methodology of weather monitoring using a ground AWS network with lightning sensors and micro-satellites weighting about 50kg, which will realize quasi-real-time thunderstorm monitoring with broad coverage. Based on the AWS network data, we plan to operate micro-satellites in nearly real-time, manipulating the attitude of satellite for capturing the most dangerous or important cloud images for 3D reconstruction. We have developed and launched several micro-satellites and been improving the target pointing operation for this decade. We succeeded in obtaining the images of the typhoon center at a resolution of 60-100 m for Typhoon Trami in 2018 and Typhoon Maysak in 2020. Using 4 or a few 10s images captured from different angles by one micro-satellite when it passed over the typhoon area, 3D models of typhoon eye were reconstructed, which have a ground resolution of ~100 m. Due to the unusual temperature profile around typhoon eye, it’s very difficult to estimate the heigh distribution of cloud top only with a thermal infrared image at a resolution of 2 km taken by geostationary meteorological satellite. This is one of the biggest limitations in estimating the precise intensity of typhoons, namely, the center pressure or the maximum wind velocity. The on-demand flexible operation of micro-satellite will achieve the high accuracy estimation of typhoon intensity as well as the speed estimation of individual thunderstorm development, which can be applied to disaster management. This research was conducted by a mixed team of Japan and the Philippines, supported by Science and Technology Research Partnership for Sustainable Development (SATREPS), which is funded by Japan Science and Technology Agency (JST) / Japan International Cooperation Agency (JICA).
Biogeochemical disruptions across the Cretaceous-Paleogene boundary : insights from sulfur isotopes
Authors: Jouini Arbia
Published: March 2021

Biogeochemical disruptions across the Cretaceous-Paleogene boundary : insights from sulfur isotopes

 

Arbia JOUINI1*, Guillaume PARIS1, Guillaume CARO1, Annachiara BARTOLINI2

1 Centre de Recherches Pétrographiques et Géochimiques, CRPG-CNRS, UMR7358, ,15 rue Notre Dame des Pauvres, BP20, 54501Vandoeuvre-lès-Nancy, France, email:Arbia.jouini@univ-lorraine.Fr

2 Muséum National D’Histoire Naturelle, Département Origines & Evolution, CR2P MNHN, CNRS, Sorbonne Université, 8 rue Buffon CP38, 75005 Paris, France

 

The Cretaceous–Paleogene (KPg) mass extinction event 66 million years ago witnessed one of the ‘Big Five’ mass extinctions of the Phanerozoic. Two major catastrophic events, the Chicxulub asteroid impact and the Deccan trap eruptions, were involved in complex climatic and environmental changes that culminated in the mass extinction including oceanic biogenic carbonate crisis, sea water chemistry and ocean oxygen level changes. Deep understanding of the coeval sulfur biogeochemical cycle may help to better constrain and quantify these parameters.

Here we present the first stratigraphic high resolution isotopic compositions of carbonate associated sulfate (CAS) based on monospecific planktic and benthic foraminifers' samples during the Maastrichtian-Danian transition from IODP pacific site 1209C. Primary δ34SCAS data suggests that there was a major perturbation of sulfur cycle around the KPg transition with rapid fluctuations (100-200kyr) of about 2-4‰ (±0.54‰, 2SD) during the late Maastrichtian followed by a negative excursion in δ34SCAS of 2-3‰ during the early Paleocene.

An increase in oxygen levels associated with a decline in organic carbon burial, related to a collapse in primary productivity, may have led to the early Paleocene δ34SCAS negative shift via a significant drop in microbial sulfate reduction. Alternatively, Deccan volcanism could also have played a role and impacted the sulfur cycle via direct input of isotopically light sulfur to the ocean. A revised correlation between δ34SCAS data reported in this study and a precise dating of the Deccan volcanism phases would allow us to explore this hypothesis.

Keywords : KPg boundary, Sulphur cycle, cycle du calcium, Planktic and benthic foraminifera

 
Neoglacial increase in high-magnitude Glacial Lake Outburst Flood frequency (Baker River, Patagonia, 47°S)
Authors: Bertrand Sebastien , Vandekerkhove Elke , Mauquoy Dmitri , McWethy Dave , Reid Brian , Stammen Sarah , Saunders Krystyna , Torrejon Fernando
Published: March 2021

Glacial Lake Outburst Floods (GLOFs) constitute a major hazard in periglacial environments. Despite a recent increase in the size and number of glacial lakes worldwide, there is only limited evidence that climate change is affecting GLOF frequency. In Patagonia, GLOFs are particularly common in the Baker River watershed (47°S), where 21 GLOFs occurred between 2008 and 2017 due to the drainage of Cachet 2 Lake into the Colonia River, a tributary of the Baker River. During these GLOFs, the increased discharge from the Colonia River blocks the regular flow of the Baker River, resulting in the inundation of the Valle Grande floodplain, which is located approximately 4 km upstream of the confluence. To assess the possible long-term relationship between GLOF frequency, glacier behavior, and climate variability, four sediment cores collected in the Valle Grande floodplain were analyzed. Their geophysical and sedimentological properties were examined, and radiocarbon-based age-depth models were constructed. All cores consist of dense, fine-grained, organic-poor material alternating with low-density organic-rich deposits. The percentage of lithogenic particles, which were most likely deposited during high-magnitude GLOFs, was used to reconstruct the flood history of the last 2.75 kyr. Results show increased flood activity between 2.57 and 2.17 cal kyr BP, and between 0.75 and 0 cal kyr BP. These two periods coincide with glacier advances during the Neoglaciation. Our results suggest that GLOFs are not a new phenomenon in the region. Although rapid glacier retreat is likely responsible for high GLOF frequency in the 21st century, high-magnitude GLOFs seem to occur more frequently when glaciers are larger and thicker.