bluuebunny/crossref_metadata_2025 huggingface dataset:
On the constitutive equations for coupled chemical reaction and deformation of porous rocks
Authors: Podladchikov Yury , Yarushina Viktoriya , Malvoisin Benjamin
Published: March 2021

Deformation, chemical reactions, and fluid flow in the geological materials are coupled processes. While some reactions are thought to be a consequence of fluid assisted dissolution on the stressed mineral surfaces and precipitation on the free surface, other reactions are caused by mineral replacement wherein a less stable mineral phase is replaced by a more stable phase, involving a change in solid volume and build-up of stresses on grain contacts, also known as a force of crystallization. Most of the existing models of chemical reactions coupled with fluid transport either assume dissolution-precipitation process or mineral growth in rocks. However, dissolution-precipitation models used together with fluid flow modelling predict a very limited extent of reaction hampered by pore clogging and blocking of reactive surfaces, which will stop reaction progress due to the limited supply of fluid to reactive surfaces. Yet, field observations report that natural rocks can undergo 100% hydration/carbonation. Mineral growth models, on the other hand, preserve solid volume but do not consider its feedback on porosity evolution. In addition, they predict the unrealistically high force of crystallization on the order of several GPa that must be developed in minerals during the reaction. Here, using a combination of effective media theory and irreversible thermodynamics approaches, we propose a new model for reaction-driven mineral expansion, which preserves porosity and limits unrealistically high build-up of the force of crystallization by allowing inelastic failure processes at the pore scale. To fully account for the coupling between reaction, deformation, and fluid flow we derive macroscopic poroviscoelastic stress-strain constitute laws, that account for chemical alteration and viscoleastic deformation of porous rocks. These constitutive equations are then used to simulate the reactive transport in porous rocks.
EnVAR for ICON-LAM: observations and quality control
Authors: Burba Mareike , Ulbrich Sven , Hollborn Stefanie , Potthast Roland , Knippertz Peter
Published: March 2021

The German Weather Service (DWD) introduces the regional NWP model ICON-LAM (ICON Limited Area Mode) in 2021 to replace the COSMO model. For the ICON-LAM data assimilation, a novel EnVAR (Ensemble VARiational data assimilation) setup is currently evaluated in comparison to the operational deterministic run of KENDA-LETKF (Local Ensemble Transform Kalman Filter). This requires special care as the observation handling differs for the global assimilation (via EnVAR) and the regional assimilation (KENDA). Furthermore, the variational quality control for the regional EnVAR may require a setup differing from the global setup. We will give an introduction to the observation processing in DWD's data assimilation framework (DACE).

For future development, we give an outlook on how a regional EnVAR can be used for a regional deterministic analysis by using a global ICON ensemble in combination with a regional deterministic ICON-LAM run. This is potentially of interest for DWD's partners with smaller computational capacities, because a regional EnVAR analysis is computationally less expensive than running a full KENDA ensemble assimilation cycle.
Does change in the upstream snowpack properties contribute to desiccation of Lake Urmia?
Authors: Saeedy Ehsan , Sima Somayeh , Atakhorrami Meysam
Published: March 2021

Lake Urmia, the largest hypersaline lake in the Middle East has desiccated significantly during the past two decades. Zarrineh River Basin (ZRB), is the largest upstream basin of Lake Urmia and supplies about half of the lake inflows. We investigated 20-years of snowpack properties of this mountainous basin including snow cover area, albedo, depth, and snow water equivalent using MODIS satellite data. We found that maximum and median snow cover area, albedo, the extent and duration of deep snow have been decreased since 2010, particularly at high altitudes. Furthermore, we observed a shift in the timing of snow accumulation and depletion since 2010. These variations have led to slightly decreased inflows to the Bukan reservoir that is the main regulator of Lake Urmia inflows. However, even in those years that the share of snowmelt runoff was high, reservoir releases have not led to more water supply to Lake Urmia due to irrigation consumption. Finally, we indicated that inflows to the Bukan Reservoir and Lake Urmia have been negatively influenced by snowpack reduction. But human decisions play a more crucial role on how to use the increased snowmelt-runoff in wet years to restore the desiccated lake through improved environmental flow allocations.  
Northward motion of the Burma Terrane alongside India during the Cenozoic.
Authors: Westerweel Jan , Roperch Pierrick , Dupont-Nivet Guillaume , Licht Alexis , Cogne Nathan , Poblete Fernando
Published: March 2021

Recent paleomagnetic data from early Late Cretaceous and late Eocene rocks from Myanmar (1,2) demonstrate that the Burma Terrane (BT) underwent an important northward translation alongside India in the Cenozoic. We present new paleomagnetic results from Paleocene to Eocene sediments that confirm the slightly southern to equatorial paleolatitudes during the Paleocene to mid Eocene. However, these paleomagnetic results imply a new paleogeography not compatible with the typical view of the geology of Myanmar as an andean-type margin above an active subduction of the Tethys/India oceanic crust below Sundaland.  Most previous models proposed an active subduction below Myanmar during the Paleogene but a slab anchored in the mantle would impede the large northward motion of the BT implied by our paleomagnetic data. We thus review the geology of the BT in light of the new latitudinal constraints provided by the paleomagnetic data. The BT contains >10km thick Cenozoic basins (Central Myanmar Basins (CMBs)) recording the Cenozoic geological evolution of the BT. The CMBs were previously interpreted with sediment sources located within the Myanmar magmatic arc and to the east in Sibumasu. The numerous studies on detrital zircons from the Late Cretaceous - Paleogene sediments  of  the CMBs highlight a clear correlation in the distribution of the ages of the pre-Cretaceous zircons (~40% of the zircons in the sediments) with the one from the Triassic turbidites (Pane Chaung Formation) of the Indo-Burman Ranges and the Triassic sediments from the Tethyan Himalaya (Langjiexue Fm.). Thus, the source of sediments is unlikely to be in Sibumasu but proposed to be in an actively eroding north-western extension of the Indo-Burman ranges (Greater Burma block, (2)) possibly linked to the Tethyan Himalaya and consistent with a BT position within the India plate during the Cenozoic. In any case, we find little evidence for a nearby active magmatic arc in the detrital zircon record supporting the hypothesis of an active subduction below the BT. Thus this review of the geology of the BT supports a rapid northward moving BT alongside India during the Cenozoic. We will discuss the implication of this new paleogeography on the India-Asia collision models.

(1) Westerweel et al. « Burma Terrane Part of the Trans-Tethyan Arc during Collision with India According to Palaeomagnetic Data ». Nature Geoscience 12, no 10 (octobre 2019): 863‑68. https://doi.org/10.1038/s41561-019-0443-2.

(2) Westerweel et al. « Burma Terrane Collision and Northward Indentation in the Eastern Himalayas Recorded in the Eocene‐Miocene Chindwin Basin (Myanmar) ». Tectonics 39, no 10 (octobre 2020). https://doi.org/10.1029/2020TC006413.
Nutrient cycling differs between cropped soils with century-old and recently pyrolyzed biochar
Authors: Burgeon Victor , Fouché Julien , Garré Sarah , Heidarian-Dehkordi Ramin , Colinet Gilles , Cornelis Jean-Thomas
Published: March 2021

The amendment of biochar to soils is often considered for its potential as a climate change mitigation and adaptation tool through agriculture. Its presence in tropical agroecosystems has been reported to positively impact soil productivity whilst successfully storing C on the short and long-term. In temperate systems, recent research showed limited to no effect on productivity following recent biochar addition to soils. Its long-term effects on productivity and nutrient cycling have, however, been overlooked yet are essential before the use of biochar can be generalized.

Our study was set up in a conventionally cropped field, containing relict charcoal kiln sites used as a model for century old biochar (CoBC, ~220 years old). These sites were compared to soils amended with recently pyrolyzed biochar (YBC) and biochar free soils (REF) to study nutrient dynamics in the soil-water-plant system. Our research focused on soil chemical properties, crop nutrient uptake and soil solution nutrient concentrations. Crop plant samples were collected over three consecutive land occupations (chicory, winter wheat and a cover crop) and soil solutions gathered through the use of suctions cups inserted in different horizons of the studied Luvisol throughout the field.

Our results showed that YBC mainly influenced the soil solution composition whereas CoBC mainly impacted the total and plant available soil nutrient content. In soils with YBC, our results showed lower nitrate and potassium concentrations in subsoil horizons, suggesting a decreased leaching, and higher phosphate concentrations in topsoil horizons. With time and the oxidation of biochar particles, our results reported higher total soil N, available K and Ca in the topsoil horizon when compared to REF, whereas available P was significantly smaller. Although significant changes occurred in terms of plant available nutrient contents and soil solution nutrient concentrations, this did not transcend in variations in crop productivity between soils for neither of the studied crops. Overall, our study highlights that young or aged biochar behave as two distinct products in terms of nutrient cycling in soils. As such the sustainability of these soils differ and their management must therefore evolve with time.
Sea ice changes in the Chukchi Sea over the Industrial Era based on biomarkers
Authors: Bai Youcheng , Sicre Marie-Alexandrine , Ren Jian , Jalali Bassem , Li Hongliang , Lin Long , Ji Zhongqiang , Su Liang , Zhu Qingmei , Jin Haiyan , Chen Jianfang
Published: March 2021

High-resolution palaeo-climate records documenting sea ice extent over the Industrial Era is an important source of information to fully understand the emergence and magnitude of on-going changes and better predict future climate evolution of the Arctic Ocean. In this study, source-specific highly branched isoprenoids (HBIs) and phytosterols were measured in multicores retrieved from the Chukchi shelf region to document the history of seasonal sea ice in this area since the beginning of the Industrial Era. HBIs at the end of the 19th century (AD 1865-1875) point to a retreat of the sea ice edge and rapid return to colder conditions. After 1920-1930 AD, proxy records indicate a steady sea ice retreat reaching a maximum in the 1990s. Sympagic biomarker IP25 and HBI II were generally low during negative Arctic Oscillation (AO) (i.e., before 1920s) while higher values were found during positive AO, in particular in the 1990s. Our data also suggest a role of remote ocean circulation features.

Among existing indices for semi-quantitative of sea ice concentration, the H-Print % sea ice index seems to generally perform less than so-called phytoplankton marker-IP25 (PIP25) index to estimate spring sea ice concentration (SpSIC). However, PBIP25-derived SpSIC better reproduce decadal scale variability and the long-term sea ice decline since the mid-20th century. Our results also highlight the lack of data for improving the PIP25 and their relationship to sea ice.
Quantifying Methane Emissions from Super-emitter Coal Mines using TROPOMI Observations
Authors: Sadavarte Pankaj , Pandey Sudhanshu , Maasakkers Joannes D. , Lorente Alba , Borsdorff Tobias , Denier van der Gon Hugo , Houweling Sander , Aben Ilse
Published: March 2021

In the context of the Paris Agreement goal of limiting global warming to below 2 degrees Celsius, the Representative Concentration Pathways (RCP) 2.6 of the Intergovernmental Panel on Climate Change (IPCC) have framed greenhouse gas emission scenarios emphasizing a sharp reduction in methane (CH4) emissions with the current increasing trend. Recent studies have shown that satellite observations of atmospheric methane can be used to detect and quantify localized methane sources on a facility-level for the oil and gas industry. We use satellite observations from TROPOMI to understand the high and persistent methane signals from ventilation shafts in the coal mining industry.  Even the bottom-up and top-down global estimates infer coal mine methane responsible for ~12% of the anthropogenic methane emissions. TROPOMI onboard Sentinel-5P has a ground pixel resolution of 5 × 7 km2 at nadir, which allows detection of large local to point sources. With its daily global coverage, we identify high methane emission sources over coal mine regions in Australia during 2018 and 2019 and quantify methane emissions using the fast data-driven cross-sectional flux method. Our initial results show that TROPOMI estimates are higher than bottom-up global emission inventories. We will present emission estimates using satellite-based quantification for super-emitter coal mines and evaluate its implication on national greenhouse gas reporting.
From global forecasts towards regional decision support: development of a full-fledged seasonal forecasting framework for semi-arid regions
Authors: Lorenz Christof , Portele Tanja , Kukuk Thomas , Kunstmann Harald
Published: March 2021

Seasonal hydrometeorological forecasts have the potential to significantly improve the regional water management, disaster preparedness and climate proofing, particularly in water-scarce regions. They also allow for the development of forecast-based action plans for extreme climatic events like droughts and anomalous wet conditions. However, raw global products from data providers like the European Centre for Medium Range Weather Forecasts (ECMWF) cannot be directly used for regional applications due to model biases and drifts as well as a coarse spatial resolution of 35km and more. Furthermore, for transferring the information from ensemble-based forecasts into practice, we have to provide derived and tailormade forecast quantities for the water management in a user-friendly way. In this study, we hence present an operational post-processing and online decision support system with which we a) regionalize ECMWF’s latest seasonal forecast system SEAS5 through a Bias-Correction and Spatial Disaggregation (BCSD) technique, b) compute tailored forecast measures like categorical forecast and drought indicators and c) visualize this information through an online platform. As reference, we are using the offline re-run of ERA5’s land surface component, namely ERA5-Land. Our final forecast product comprises daily ensemble forecasts for precipitation, temperature, and radiation, has a spatial resolution of 0.1°, covers the whole period from 1981 to the present and is provided for several climate-sensitive river-basins including the Rio São Francisco (Brazil), the Blue Nile (Sudan / Ethiopia) and the Karun (Iran). Derived forecast quantities are operationally computed and visualized through an online decision support system, that was jointly developed with water experts from the different study regions. As both the forecast repository and the online decision support system are publicly available, they provide a comprehensive framework for demonstrating how seasonal forecasts can be post-processed and tailored for the day-to-day water management. They further allow for the training and education of local stakeholders and water experts how to deal with seasonal forecasts. Our forecasting system is already used by several authorities and weather services in Iran, Sudan and Brazil. It thereby constitutes a large step towards an improved disaster preparedness and, hence, the climate proofing of the water sector particularly in these semi-arid regions.
Evaluating parametric sensitivity of climate feedbacks in CNRM-CM6
Authors: Peatier Saloua , Sanderson Benjamin , Terray Laurent
Published: March 2021

The global surface temperature response to CO2 doubling (Equilibrium Climate Sensitivity or ECS) is a key uncertain parameter determining the extent of future climate change. Sherwood et al. (2020) estimated the ECS to be within [2.6K - 4.5K], but in the Coupled Model Intercomparison Project phase 6 (CMIP6), 1/3 of the General Circulation Models (GCMs) show ECS exceeding 4.5K (Zelinka et al., 2020). CNRM-CM6-1 is one of these models, with an ECS of 4.9K. In this paper, we sampled 30 atmospheric parameters of CNRM-CM6-1 and produced a Perturbed Physics Ensemble (PPE) of atmospheric-only simulations to explore the feedback parameters diversity and the climatological plausibility of the members. This PPE showed a comparable  range of feedback parameters to the multi-model archive, from 0.8 W.m-2/K to 1.8 W.m-2/K. Emulators of climatological performance and feedback parameters were used together with  observational datasets to search for optimal model configurations conditional on different net climate feedbacks. The climatological constraints considered here did not themselves rule out the higher end ECS values of 5K and above. An optimal subset of parameter configurations were chosen to sample the range of ECS allowing the assessment of feedback constraints in future fully coupled experiments.

 

References :

Sherwood, S. C., Webb, M. J., Annan, J. D., Armour, K. C., Forster, P. M., Hargreaves, J. C., ... & Zelinka, M. D. (2020). An assessment of Earth's climate sensitivity using multiple lines of evidence. Reviews of Geophysics, 58(4), e2019RG000678.

Zelinka, M. D., Myers, T. A., McCoy, D. T., Po‐Chedley, S., Caldwell, P. M., Ceppi, P., ... & Taylor, K. E. (2020). Causes of higher climate sensitivity in CMIP6 models. Geophysical Research Letters, 47(1), e2019GL085782.
Temporal variation of particle precipitation in Erath's polar cap from DMSP observations
Authors: Huang Yanshi , Liang Shan
Published: March 2021

Previous observations and simulations have shown that the low-energy electron precipitation in the cusp plays an important role in ionosphere and thermosphere through particle impact ionization and heating. In this study, we investigate the precipitating particles in the Earth's polar cap region, which is also an open-field line region as the cusp. In many numerical simulations of the upper atmosphere, the polar cap region is described as a uniform area with no spatial and temporal variations of the particle energy and fluxes. We analyze years of the particle observations from DMSP satellites to show the temporal variations of particle characteristics in the region poleward of 80 degree magnetic latitudes in this study. The results show the solar cycle, annual and seasonal variations of particle (electrons, ions) energy, number flux and energy flux in the polar cap. The results will be useful to improve the polar-latitude precipitating particle description in upper atmosphere modeling.
Soil erosion and overland flow in Japanese cypress plantations: Spatio-temporal variations and a sampling strategy.
Authors: Sato Takanori , Tanaka Nobuaki , Nainar Anand , Kuraji Koichiro , Gomyo Mie , Suzuki Haruhiko
Published: March 2021

Many studies have focused on soil erosion in unmanaged Japanese cypress plantations because the sparse understory vegetation and litter covering the forest ground enhance soil erosion. Many studies also indicated that soil erosion and overland flow have large spatial variation. However there are less studies focusing on sampling strategy to obtain the slope scale soil erosion and overland flow in forested slope area. In this study, soil erosion, litter, and overland flow measurements were conducted over 14 months (March 2016 to April 2017) to identify the spatio-temporal variation and examine the optimal sample size in an unmanaged Japanese cypress plantation located in Aichi Prefecture, Japan. We used small-sized traps to collect sediment, litter and overland flow simultaneously. These traps with dimensions of 0.15 × 0.25 × 0.20 m (height × width × depth) was made by stainless- steel. Each trap was connected to a storage plastic tank installed downslope of trap to store the overland flow. To capture sediment and litter, the outlet of downslope-facing trap was wrapped by 1 mm mesh. To estimate the sediment that passed this mesh, water stored in the plastic tank was sampled to obtain the sediment concentration. Fifteen traps were installed in line along the bottom of a 15-m wide slope. The sampling interval was approximately 1 month. The range across all traps in terms of soil erosion was 79.2 to 596.8 g m-1, while for litter it was 132.8 to 246.4 g m-1 and for overland flow, 42.0 to 612.4 L m-1. The temporal coefficient of variation of soil erosion and overland flow was highest during dry seasons, while smaller during wet seasons. These results indicated that soil erosion and overland flow had larger spatio-temporal variations as compared to litter. To examine the relationship between sample size (number of traps) and potential errors caused by the spatio-temporal variation of soil erosion, litter and overland flow measurements, stratified Monte Carlo random sampling was performed. This random sampling analysis showed that the rate of decrease in spatio-temporal variation became moderate as the sample size increased beyond six. This result indicated that the optimal sample size was five, the total width of which was equivalent to about 8% of the monitored slope width.
Western boundary circulation and sea level patterns in northern hemisphere oceans
Authors: Diabaté Samuel , Swingedouw Didier , Hirschi Joël , Duchez Aurélie , Leadbitter Philip , Haigh Ivan , McCarthy Gerard
Published: March 2021

The sea level changes along the Atlantic coast of the US have received a lot of attention recently because of an increased rate of rise north of the Gulf Stream separation point since the late 1980s (Sallenger et al., 2012 ; Boon, 2012). While sea-level rise is a major issue for coastal community, sea-level measurements in the region are key to understand the past of the nearby Gulf Stream and the large-scale ocean dynamics. Tide gauges on the coastline have measured the inshore sea-level for many decades and provide a unique window on past oceanic circulation. So far, numerous studies have linked the interannual to multi-decadal coastal sea-level changes to ocean dynamics, including the Gulf Stream strength, the divergence of the Sverdrup transport in the basin interior and the Atlantic meridional overturning circulation. However, other studies argue that local and regional processes, such as the alongshore winds or the river discharges, are processes of greater importance to the coastal sea level.

The general picture in the Atlantic is hence unclear. Yet, the northwest Atlantic is not the only western boundary region where sea-level has been well sampled. In this study we extend the analysis to the northwest Pacific, where links between the state of the Kuroshio and sea-level are evident (Kawabe, 2005; Sasaki et al., 2014). We discuss similarities and dissimilarities between the western boundary regions. We show for each basin, that the inshore sea level upstream the separation points is in sustained agreement with the meridional shifts of the western boundary current extension. This indicates that long duration tide gauges, such as Fernandina Beach (US) and Hosojima (Japan) could be used as proxies for the Gulf Stream North Wall and the Kuroshio Extension state, respectively.

References:

Boon, J. D. (2012). Evidence of sea level acceleration at US and Canadian tide stations, Atlantic Coast, North America. Journal of Coastal Research, 28(6), 1437-1445. 

Kawabe, M. (2005). Variations of the Kuroshio in the southern region of Japan: Conditions for large meander of the Kuroshio. Journal of oceanography, 61(3), 529-537.

Sallenger, A. H., Doran, K. S., & Howd, P. A. (2012). Hotspot of accelerated sea-level rise on the Atlantic coast of North America. Nature Climate Change, 2(12), 884-888.

Sasaki, Y. N., Minobe, S., & Miura, Y. (2014). Decadal sea‐level variability along the coast of Japan in response to ocean circulation changes. Journal of Geophysical Research: Oceans, 119(1), 266-275.
Antimony and arsenic distribution and impacts at a derelict antimony mine in Scotland 
Authors: Mbadugha Lenka , Cowper Duncan , Dossanov Sapar , Paton Graeme
Published: March 2021

Mining activities are acknowledged to introduce contaminants into localised environments and cause wider spread diffuse pollution. The concentration, distribution and fate of arsenic (As) and antimony (Sb) were studied at the former metalliferous Louisa Mine at Glendinning, Scotland. The associated deposit is one of very few able to produce Sb in the UK and was mined for three brief periods between 1793 and 1922.  

The remnants of the mine consist of the ore processing area and two spoils. Soils withing these zones as well as around the mine were sampled and complemented by water samples from the adjacent stream, the Glennshanna Burn. All samples were subsequently analysed to map the distribution of contamination and identify pollution sources. The maximum concentrations of As and Sb, 15490 and 1504.2 mg kg−1 respectively, were determined in soils associated with the ore processing area and spoil heaps. Anthropogenic activities also redistributed As and Sb within these mine zones and altered their relative ratios. The fractions of dissolved As and Sb in soils were < 1 and < 5% of total soil content, respectively, confirming findings of previous studies that As and Sb are relatively immobile. Yet, the concentrations of As and Sb released by soils exceeded regulatory limits.

Concentrations of As and Sb in surface water in the immediate vicinity of the mine were impacted by a gully discharge, but rapidly diluted. While the concentrations affected by the run-off waters did not exceed EU environmental standards for freshwater, the concentrations of As and Sb sharply increased to 11.43 ± 3.43 and 9.28 ± 0.59 μg l−1, respectively, approximately 100 m downstream of the mine site. The unaltered As to Sb ratios in water samples suggested a geogenic source of contamination.

While there is a justifiable concern about the soil pollution caused by the historic mining in the studied area, the Glenshanna Burn is affected more by indigenous geochemical processes than the derelict mine.
 Evaluation of high resolution WRF forecasts for Extreme Rainfall Events over Karnataka against high density in-situ observations 
Authors: Bankar Ajay , Vasudevan Rakesh
Published: March 2021

Extreme Rainfall Events (EREs) in India has increased many folds in recent decades. These severe weather events are generally destructive in nature causing flash floods, catastrophic loss of life and property over densely populated urban cities. Various cities in Karnataka, a southern state in India, witnessed many EREs recently. Appropriate advanced warning systems to predict these events are crucial for preparedness of mitigation strategy to reduce human casualty and socio economic loss. Mesoscale models are essential tools for developing an integrated platform for disaster warning and management. From a stakeholder/user pint of view, primary requirement to tackle ERE related damages is accurate prediction of the observed rainfall location, coverage and intensity in advance. Weather prediction models have inherent limitations imposed primarily by approximations in the model and inadequacies in data. Hence, it is important to evaluate the skill of these models for many cases under different synoptic conditions to quantify model skill before using them for operational applications. The objective of the study is to evaluate performance of the Weather Research and Forecasting (WRF) model for several ERE cases in Karnataka at different model initial conditions. The EREs were identified from the distribution of rainfall events over different regions in Karnataka and those events comes under 1% probability were considered. We examined 38 ERE’s distributed over Karnataka for the period June to November for the years 2015-2019. WRF model is configured with 3 nested domains with outer, inner and innermost domains having resolution of 12 km, 9 km and 3 km respectively. Two sets of simulations are conducted in this study, i) staring at 12 hours prior to the ERE day (i.e. -1200 UTC) & ii) starting at 0000 UTC of the ERE day. Performance of the WRF model forecast is validated against 15 minutes rainfall observations from ~6000 rain gauge stations over Karnataka. During initial hours forecasts initiated at 1200 UTC has distinct advantage in terms of accuracy compared to those initiated at 0000 UTC for most of the cases. In general, model underpredict EREs and underprediction is relatively low for forecasts initiated at 12 00 UTC.
Application of earth observation datasets and Analytic Hierarchy Process in the mapping of Landslide hazard zones of Manipur, India
Authors: Singh Digvijay , Laha Arnab
Published: March 2021

Landslides problems are one of the major natural hazards in the mountainous region. Every year due to the increase in anthropogenic factors and changing climate, the problem of landslides is increasing, which leads to huge loss of property and life. Landslide is a common and regular phenomenon in most of the northeastern states of India.  However, in recent past years, Manipur has experienced several landslides including mudslides during the rainy season. Manipur is a geologically young and geodynamically active area with many streams flowing parallel to fault lines. As a first step toward hazard management, a landslide susceptibility map is the prime necessity of the region. In this study, we have prepared a landslide hazard map of the state using freely available earth observations datasets and multi-criteria decision making technique, i.e., Analytic Hierarchy Process (AHP). For this purpose, lithology, rainfall, slope, aspect, relative relief, Topographic Wetness Index, and distance from road, river and fault were used as the parameters in AHP based on the understanding of their influence towards landslide in that region. The hazard map is classified into four hazard zones: Very High, High, Moderate, and Low. About 40% of the state falls under very high and high hazard zone, and the hilly regions such as Senapati and Chandel district are more susceptible to the landslide. Among the factors, slope and rainfall have a more significant contribution towards landslide hazard. It is also observed that areas nearer to NH-39 that lies in the fault zones i.e., Mao is also susceptible to high hazard. The landslide susceptibility map gives an first-hand impression for future land use planning and hazard mitigation purpose.
Seismic Body-Wave Tomography in Fennoscandia
Authors: Bulut Nevra , Maupin Valerie , Thybo Hans
Published: March 2021

We present a seismic tomographic image of Fennoscandia based on data from the ScanArray project in Norway, Sweden, and Finland, which operated during 2012-2017, together with data from earlier projects and stationary stations. We use relative traveltime residuals of P- and S- waves in high- and low-frequency bands and apply the frequency-dependent crustal correction. We use seismic signals from earthquakes at epicentral distances between 30° and 104° and magnitudes larger than 5.5. The general purpose of this study is to understand the possible causes of the high topography in Scandinavia along the passive continental margins in the North Atlantic as well as the interrelation between structure at the surface and in the lithospheric mantle.

We present an upper-mantle velocity structure for most Fennoscandia derived for the depth range 50-800 km with a 3D multiscale parameterization for an inversion mesh-grid with dimensions dx=dy=17.38 km and dz=23.44 km. In all body-wave tomography methods, smearing of anomalies is expected. Therefore resolution tests are critical for assessing the resolution of the parameters determined in the velocity models. The resolution of the models depends on several factors, including the noise level and general quality of data, the density of observations, the distance and back-azimuthal distribution of sources, the damping applied, and the model parameterization. We use checkerboard and model-driven (block and cylindrical) tests for assessing the resolution of our models.

Seismic models derived in this study are compared to existing and past topography to contribute to understanding mechanisms responsible for the topographic changes in the Fennoscandian region. The models also provide a basis for deriving high-resolution models of temperature and compositional anomalies that may contribute to understanding the observed, enigmatic topography.
Linking submesoscale fronts and air-sea heat fluxes in the Southern Ocean: Results from the first Saildrone circumnavigation of Antarctica
Authors: Rosenthal Hanna S. , Biddle Louise C. , Swart Sebastiaan , Gille Sarah T. , Mazloff Matthew R.
Published: March 2021

The role of the Southern Ocean in the global heat and carbon cycle is fundamental towards our climate, but observational data to quantify air-sea fluxes, such as surface  heat  fluxes, are  still  scarce. In  order  to  investigate  the  effects  of  fine- scale oceanic fronts (0.1 km–10 km) on air-sea fluxes in the Southern Ocean, high-resolution  hydrographic  and  meteorological  data  collected  by  three  un-crewed surface vehicles (Saildrones) during their first Circumnavigation of Antarctica in 2019 was assessed. Comparisons of key variables from the in situ Saildrones datasets with those from ERA5 and a stationary mooring show good  agreement.  Temperature-driven density fronts were detected in the Saildrone data and their impact on the turbulent heat flux was quantified during steady atmospheric conditions.  Over 2000 surface ocean temperature dominated density fronts were detected at length-scales (i.e.  front width) ranging from sub-kilometer to mesoscale (order of 0.1 km–100 km). 
Temperature-driven density fronts with a length scale (as seen from the Saildrones perspective ) smaller than 1 km contributed 75% and 51% of the sensible and latent heat flux changes, respectively. The direct link between the fronts and the impact on the heat fluxes decreases sharply  when the front length increases. This suggests that smaller (submesoscale) fronts have a larger impact on heat flux variability than larger (balanced) fronts . The parametrization of  these  fine-scale ocean-atmospheric processes  in  global climate  models  could  lead to more accurate  representations  of  the  heat  flux  variability both at local and global scale.
Implicit geological modeling for the Einstein Telescope (Meuse-Rhine Euroregion)
Authors: Chudalla Nils , Wellmann Florian , Jüstel Alexander , von Harten Jan
Published: March 2021

Expectations for geological models for underground characterization rise with complex engineering tasks. In this project we examine a target area as a potential site for the gravitational-wave observatory “Einstein Telescope” in the Meuse-Rhine Euroregion (Netherlands, Belgium, Germany).  The Einstein Telescope will be the world’s most sensitive observatory of its kind. It consists of a triangular shaped facility connected by 10 km long arms in 200-300 m depth. A high accuracy 3-D structural geological model is required to constrain the best position of the Einstein Telescope with geophysical and geotechnical methods.

We use an implicit modeling approach based on surface points and orientation data for modeling. This data is extracted from seismic surveys and well logs available in the region. The application of probabilistic methods in this workflow allows to propagate uncertainty of the input data into a resulting model suite, allowing to define a measure of uncertainty for the final model. Specific local difficulties that were encountered during the modelling process, including data management, the representation of complex fault networks and scaling issues will be discussed.

We will show 3-D geological models for the Meuse-Rhine Eurogregion to significantly improve our geological understanding of the target area. This improved understanding is crucial for finding the optimal position for the Einstein Telescope. Data is managed using the open-source library GemGIS. Models are created using the open-source library GemPy.
Upscaling plant traits to ecosystem level: blending local biodiversity,  global traits databases, and remote sensing data.
Authors: Moreno-Martínez Álvaro , Adsuara Jose E. , Muñoz-Marí Jordi , Izquierdo-Verdiguier Emma , Katge Jens , Carvalhais Nuno , Reichstein Markus , Running Steven W. , Camps-Valls Gustau
Published: March 2021

Plant functional traits have great influence in how terrestrial ecosystems function. This key information is however generally oversimplified in most Earth system models (ESMs) and is typically represented by a number of static, empirically fixed values assigned to a selection of plant functional types (PFTs). This leads to reducing the diversity of plant communities into a relatively low number of categories and key variability within individual PFTs is lost. Subgrid processes are thus underrepresented and accuracy compromised.

The TRY global traits database contains the largest set of in-situ trait observations for numerous species around the globe. Despite the large number of species and samples included in trait databases, such as TRY, they are sparse compared to the overall richness and diversity of species globally. We propose the use of the massive geolocated plant occurrence data from the Global Biodiversity Information Facility (GBIF) as ancillary source of information to better capture species distributions, especially in locations where TRY data are missing. 

As a first order approach, GBIF was used to estimate species abundances for a given study area (contiguous United States), and they were further corrected with high resolution, subpixel maps of PFT derived via remote sensing and machine learning upscaling.  This information was used to provide ecosystem level trait estimates for a selection of plant traits (specific leaf area and leaf nitrogen concentration). The proposed approach allows us to link local biodiversity composition from GBIF with a more precise and realistic representation of plant community composition coming from remote sensing information for ecosystem-level trait estimation. Among many possible applications of these data, the addition of the produced trait estimates to improve ESMs estimations could be very valuable to improve the understanding and monitoring of the biosphere.
Speleothems as recorders of local climate variability and its implications for Maya cultural evolution from a unique cave site on the northern Yucatán Peninsula
Authors: Schorndorf Nils , Frank Norbert , Warken Sophie , Förstel Julius , Schröder-Ritzrau Andrea , Avilés Olguín Jerónimo , Stinnesbeck Wolfgang
Published: March 2021

The unsteady cultural evolution and final collapse of Maya civilization in Mesoamerica are heavily debated issues and discussion includes the impact of both natural (e.g., droughts, hurricanes, volcanic eruptions) and social disasters (e.g., warfare and unsustainable economy). An increasing number of records point to recurrent multi-year droughts coinciding with hiatuses in construction, periods of temporary urban abandonment and population collapse. Previous reconstructions indicate that environmental conditions and precipitation on the Yucatán Peninsula were distributed very heterogeneously in space and time and the duration and chronology of events remains uncertain. High resolution environmental reconstructions are, however, mainly based on archives from sites on the southern Yucatán Peninsula.

We have now recovered several stalagmites from Estrella Cave, northern Yucatán Peninsula, spanning the entire Maya era and reaching even to historical times (−1100 to 1780 AD). The high precision 230Th/U ages obtained so far from these stalagmites indicate growth rates of up to 160 µm per year, thus offering the potential for annual to decadal climate proxy reconstruction. Here we present 230Th/U based preliminary age models for some of these stalagmites. Based on growth rates, petrographic observations, and trace element to calcium ratios we draw first conclusions on the timing of (recurrent) dry periods around key episodes of Maya cultural evolution, such as the Terminal Classic Period (~800–1000 AD). Furthermore, these first results show that the incorporation of certain trace elements (Mg, Sr, Ba, P, …) in these speleothems is strongly related to recharge and hence precipitation above the cave. Moreover, the site also contains unique remains of the Mayan culture, such as paintings, pottery, constructions and even buried skeletons, thus highlighting its significance not only for regional climate reconstruction but also for local archaeology.
Estimating the global frequency, magnitude, and hazard of glacier lake outburst floods
Authors: Veh Georg , Lützow Natalie , Kharlamova Varvara , Petrakov Dmitry , Hugonnet Romain , Korup Oliver
Published: March 2021

Many thousands of glacier lakes have formed from glacier retreat in high mountains since the beginning of the 20th century. These water bodies are impounded by glaciers and moraines and can release sudden glacier lake outburst floods (GLOFs), with potentially disastrous downstream consequences. Estimates of GLOF frequency, magnitude, and hazard at global or regional scales remain controversial because of unsystematic reports and inconsistent regional flood databases. We compile the largest GLOF inventory to date, containing 2,000 cases (AD 1901—2018) from 700 different sources. We find that the annual number of reported GLOFs has increased more than fivefold in our study period. This increase could be due to physical reasons such as atmospheric warming or because of growing research interest in glaciers. We tested this notion by comparing annual GLOF counts with the annual number of glacier surveys and the mean annual temperature extracted from all burst lakes. Our models show that research interest in glaciers has a higher impact on GLOF reporting, suggesting that historic documentation in earlier decades was likely biased towards more accessible mountain ranges such as the European Alps. Despite improved GLOF detection, reported flood volumes and peak discharges have become smaller since the 1960s. We analysed volume changes of glaciers that dammed burst lakes, and found that these glaciers have thinned considerably in past decades. Rapidly melting glaciers may thus impound smaller lakes and produce floods of decreasing magnitudes. Using extreme-value statistics, we will investigate how GLOF return periods or return levels have changed in past decades. Our regional GLOF hazard assessment will focus on mountain ranges with increasing exposure of population and infrastructure such as the Andes, the Pacific Northwest, Iceland, the European Alps, Scandinavia, and High Asia. These estimates of GLOF hazard will provide quantitative support for practitioners to identify regions that have a high demand for strategies in GLOF risk management.
Ephemeral Streams: An overlooked permanent source of groundwater and Nutrients to the Mediterranean Sea
Authors: Diego-Feliu Marc , Rodellas Valentí , Alorda-Kleinglass Aaron , Domínguez-Gabarró Júlia , Saaltink Maarten , Folch Albert , Garcia-Orellana Jordi
Published: March 2021

Fluxes of nutrients, metals, contaminants, among others dissolved compounds transported from land to oceans have a direct impact on coastal biogeochemical cycles. One of these land-ocean interaction mechanisms, recently recognized as an important source of these compounds, is the flow of groundwater from continental margins to the coastal ocean, commonly known as Submarine Groundwater Discharge (SGD). The Mediterranean coastline is characterized by the presence of ephemeral streams, geomorphological settings that act as preferential flow paths for both runoff and groundwater towards the sea. The Mediterranean Basin is highly influenced by strong precipitation events (>50 mm) that commonly occur during fall and spring seasons such as isolated depression at high levels events, locally named ‘gota-freda’. In such situations, runoff causes several social and environmental impacts along ephemeral streams that have been long recognized. However, when the surface water flow ceases, the subterranean part of ephemeral streams may continue supplying water and solutes to the coastal ocean via SGD. This process and its effects for coastal ecosystems have been largely overlooked. In this study, we evaluated the influence of a ‘gota-freda’ event on both the role of ephemeral streams as preferential areas for groundwater discharge and on the magnitude of SGD and SGD-derived nutrient fluxes. To do so, three seawater sampling campaigns were performed in a Mediterranean coastal region dominated by ephemeral streams (Maresme, Catalunya) after heavy rainfall events (~50 mm) and in baseflow conditions. Results of this study indicate that SGD flows are between 5 and 7 times higher after a strong precipitation event than in baseflow conditions indicating that the supply of nutrients and other dissolved compounds to the Mediterranean Sea is highly dependent on these events. This study highlights that this mechanism is a relevant process for coastal biogeochemical cycles of semi-arid regions such as the Mediterranean basin.
Riverine transport of floating macro litter to the Southeastern Black Sea
Authors: Aytan Ülgen , Şenyiğit Çağan , Şentürk Yasemen , Esensoy Başak
Published: March 2021

Marine litter, especially plastic, is the fastest growing environmental problem in the Black Sea. Rivers are recognized as the major sources of litter in the basin, but information on the transport of litter by rivers is still limited. This study presents the first estimates of riverine floating macro-litter in the SE Black Sea (Turkey), based on monthly visual counting in three relatively small rivers between January and August of 2020. Plastic represented 99 % of the identified items with fragments (2.5–50 cm) (40.3 %) and shopping bags (26.2 %) being the most abundant items. Riverine litter fluxes median values varied between 35 and 96 items/hour in three rivers. Results show that small rivers can carry a considerable amount of plastic to the SE Black Sea. This calls for increased monitoring of riverine litter transport to develop effective prevention and removal strategies for tackling the problem of plastic pollution in the Black Sea.