bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling new scenarios of ocean dynamics during deglaciation over Southern European Seas (Mediterranean and Black Seas)
Authors: Ramstein Gilles , Vadsaria Tristan , Li Laurent , Dutay Jean-Claude , Zaragosi Sébastien
Published: March 2021

During quaternary, periodic organic rich layers in the Mediterranean Sea marine sediments also known as sapropels, are not only driven by African monsoon modulation. Superimposed to the main pacing associated with precession cycles (about 21 ka) many sapropels are also impacted by the 100 ka periods associated with the glacial-interglacial cycles. The last occurrence (S1) at the end of the last glacial period and the Early Holocene is an appropriate illustration of this behavior. Recent studies based on long deglaciation simulations with coupled AOGCM pointed out that reaching bottom water anoxia needs a preconditioning, throughout the last deglaciation, driven by North Atlantic Ocean freshening for a few thousand years prior to S1. Here, we investigate another important source of fresh water induced by the melting of Fennoscandian ice sheets (FIS). This run-off freshened the Black Sea, the Marmara Sea and ultimately could have an impact on the stratification and the convection over the Aegean Sea. In order to tackle this issue, we used continental hydrologic perturbation scenarios to drive a high-resolution Mediterranean Sea dynamic circulation model (1/8°) that correctly captures the convection sites and their intensity. In one hand, we rely on hydrologic reconstruction of FIS melting provided by Peltier et al. (JGR, 2015) and Patton, H. et al. (QSR, 2017) in order to derive freshwater flux since the Last Glacial Maximum - that impacted the Black Sea, and likely the Eastern Mediterranean Sea. In the other hand, we build a complete transient scenario accounting for the later enhancement of the African monsoon and we increase fresh water from Nile river. Prescribing such a scenario: first a freshwater increase from FIS during the deglaciation and second a fresh water increase from Nile river, it leads to the shutdown of the Mediterranean Thermohaline Circulation. Our results are in good agreement with Aegean reconstructions (Grant et al, QSR, 2016; Soulet e al. Proc. Natl. Acad. Sci, 3013). The methodology we developed could also be applied to sapropel S5 and S10.
Gold fingerprint of the SCLM beneath a metallogenic province
Authors: Schettino Erwin , Marchesi Claudio , González-Jiménez José María , Saunders Edward , Hidas Károly , Gervilla Fernando , Garrido Carlos Jesús
Published: March 2021

Magmatic-hydrothermal gold deposits form clusters in the Earth’s crust and are heterogeneously distributed within lithospheric blocks. A global assessment of whole-rock gold abundances in mantle lithologies worldwide indicates that Au concentrations increase with increasing fertility of mantle peridotites, with median Au contents ranging from 0.50 ppb in dunites, 1.00 ppb in harzburgites, and up to 1.26 ppb in lherzolites. Of particular interest are those volumes of fertile Subcontinental Lithospheric Mantle (SCLM) veined by pyroxenites and wehrlites, usually the Au-richest lithologies in the mantle as they have 2.05 ppb median Au concentrations. Partial melting of SCLM domains endowed in gold seems to play a key role in the genesis of gold-enriched magmas parental to magmatic-hydrothermal gold deposits in continental arc settings. The mineralogical expressions of gold inventory in such fertile mantle rocks are accessory Ni-Fe-Cu sulfides and discrete micron-to-nano-sized Au mineral particles that control the extraction and transport of gold in the mantle. Mantle xenoliths from the Neogene Volcanic Province (NVP) of southeast Spain represent an excellent example of SCLM refertilized by gold-sulfide-rich silicate melts underlying a gold metallogenic province. Here we present mineralogical and compositional data of sulfides in mantle xenoliths from this area (Tallante volcanic center), which are anomalously rich in gold (up to 46 ppm) compared to sulfides from SCLM not associated with Au-metallogenic provinces. We propose that these gold-rich, fertile mantle sources may have melted during the Cenozoic evolution of the westernmost Mediterranean subduction system and fed the ore-productive volcanic activity in southeast Spain.
Crustal architecture of Amsterdam-St. Paul Island from an integrated geophysical approach
Authors: Kumar Pankaj , Anand Pratyush , Ghosal Dibakar , Singha Pabitra
Published: March 2021

The Amsterdam-St. Paul (ASP) island complex is a manifestation of interaction between the South-East Indian Ridge (SEIR) and the ASP mantle plume, which was formed ~10 Ma. Very few geophysical studies have been conducted over the ASP island complex and therefore we have limited information about the island so far. We performed an integrated geophysical approach using gravity, magnetic study along with the joint inversion of Ps receiver function and Rayleigh wave group velocity dispersion curve to determine the crustal architecture and Moho variation in the region. The result of integrated gravity-magnetic modeling revealed that the island complex is associated with three crustal layers beneath the sedimentary strata. Inversion of Rayleigh wave group velocity dispersion curve accounts for vertical shear wave velocity average which supported the layered velocity profile. The results revealed that magnetic material (Mid oceanic ridge basalt/Flood basalt) has carpeted the entire island causing high magnetic anomaly of -1000 to 1500 nT, which is generated by gradual accumulation of a thick pile of magnetic material of normal as well as reverse polarity. The results by integrated Gravity-magnetic model suggest that crust beneath the island is suggested to be highly affected by volcanic activity (Mantle Plume/Ridge) and is underlain by high-density underplated material. The results further suggest that SEIR has less role for the outpoured magmatic activity. Integrated Gravity-magnetic model show that Moho is variable beneath the island complex and lies in the range of ~12-17 km. Further results by joint inversion of Ps receiver function and Rayleigh wave group velocity dispersion curve for the station (AIS : Nouvelle Amsterdam - TAAF, France) suggest Moho depth of ~14 km beneath the Amsterdam island and is well in agreement with the gravity-magnetic studies. The result clearly indicates that ASP island complex is highly affected by the ASP plume activity and was evolved during the ridge-plume interaction.
The regional model of Subpolar Gyre based on NEMO 4
Authors: Verezemskaya Polina , Barnier Bernard , Molines Jean-Marc , Gulev Sergey , Gavrikov Alexander
Published: March 2021

A regional model of Subpolar Gyre in the North Atlantic is implemented. The NNATL12 model development aimed at a realistic representation of Subpolar Northern Atlantic's complex dynamics during the satellite era (starting from 1993 to nowadays) by using a high-resolution regional model that relies on the most up-to-date atmospheric and lateral forcing datasets and modeling techniques. Configuring this model, we focused on the representation of key processes in the Northern Atlantic, such as Irminger Rings, the boundary currents, deep convection, and convective eddies, dense waters cascading through the narrow straits between the Arctic and the Atlantic basins. NNATL12 model is based on NEMO4. The model domain covers the area between 47-70˚N and 84˚W-10˚E with a grid of 1/12˚ in horizontal and 75 vertical levels. In this region, the model is partially eddy-resolving. Three lateral open boundaries and initial conditions are set from the new GLORYS12 reanalysis (Lellouche et al., 2018). The surface forcing is provided by the new RAS NAAD dynamical hindcast based on the WRF model with a spatial resolution of 14 km (Gavrikov et al. 2020). The model adopted the most recent developments in the forced ocean modeling, such as upper boundary forcing schemes (Renault et al., 2020, Brodeau et al., 2016) and local-sigma vertical coordinate in the area of the overflows (Colombo et al., 2020). The model solution is sensitive to new parameterizations and vertical coordinate, which is demonstrated in various tests. The model provides a reliable estimate of the Subpolar North Atlantic circulation system at the surface and medium depth compared to observations. The model represents the ocean stratification at depths above 2000 m showing higher temperatures in the bottom of the Irminger Sea. At daily timescales, it is capable of representing the volume transport comparable to observed values. Irminger Rings TS-structure and dynamics are simulated consistent with the glider data. Comparing to the reanalysis model overestimates the March mixed layer depths and overextends the region of convection north. At the same time, the short-scale and decadal variability of MLD are reproduced by the model. Significant improvements of the deep stratification are obtained with the implementation of the local-sigma vertical coordinate. The model provides vertical profiles of temperature and salinity similar to the observed ones. However the Denmark Strait overflow waters are still too warm, but this is for a large part due to too warm waters at the sill. The high-frequency variability in the Denmark Strait is also in good accordance with the observations.
Sedimentological characterization of coarse sediments within the deglaciation sequence in the east Antarctic Wilkes Land margin
Authors: Gutierrez-Pastor Julia , Escutia Carlota , Röhl Ursula , Salabarnada Ariadna , Jimenez-Espejo Francisco
Published: March 2021

During the Holocene, 180 m of diatom ooze sediments were deposited in the Antarctic Wilkes Land margin continental shelf at site U1357A (Integrated Ocean Drilling Program Expedition 318, Escutia et al., 2011). Holocene sediments are dominated by rhythmic laminated deposits above a poorly sorted gravelly siltstone diamicton from the Last Glacial Maximum (LGM). CT-scans reveal three events of gravel/sand/silt sediments interbedded within the laminated sediments and interpreted as ice rafted debris (IRD).  Two of these events (from 185,1 to 185,45 and 174, 8 to 175,37 meters below seafloor, mbsf) are characterized by dispersed large clasts (1-5cm) within a muddy matrix at the base, transitioning to the top to millimetre-size clasts that are either aligned with the dark and light laminae or dispersed. A third event (176,2 to 177,2 mbsf) is characterized by a structureless sediment sequence with high concentrations of dispersed clasts that are up to 1-2 cm size. We used ImageJ/Fiji software, to conduct a quantitative analysis of grains bigger than 1mm in CT Scan 3D images. Measured parameters include grain size (Feret length), grain orientation (Feret angle), circularity and roundness, among other. In addition, grey scale profiles have been created from the sediment CT-scan images as a density proxy. Quantitative data and density profiles have been used to aid the sedimentological characterization of the Holocene deglaciation section and to infer depositional environment and patterns of deglaciation.

Escutia, C., Brinkhuis, H., Klaus, A., and the Expedition 318 Scientists, Proc. IODP, 318: Site 1357. Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/​iodp.proc.318.105.2011

 
On the evolution of the northern Bay of Bengal Dome.
Authors: Nambiathody Anup , Vijayakumaran Vijith , Chatterjee Abhisek
Published: March 2021

The climatologically averaged sea surface height anomaly (SSHA) during the summer monsoon in the Bay of Bengal (BoB) shows two prominent negative anomalies, one in the southern BoB and another in the northern BoB. The occurrence of negative SSHA observed in the southern BoB has been extensively studied and is linked to Sri Lanka Dome (SLD), whereas negative SSHA observed in the north has received less attention. A pronounced thermal dome develops in the northern BoB with its mean position between 86-89oE and 16-19oN, as shown by the doming of isotherms. We refer to this oceanic thermal dome as the northern BoB Dome (NBD). The present study focuses on the evolution of the NBD using observation and a coupled OGCM-biogeochemical model. The formation of NBD occurs during the summer monsoon (May - September), at a time when the wind stress curl is positive. Interestingly, the cyclonic curl is positive in the entire northern BoB, yet the negative SSHA is confined to a small region. Our analysis shows that strong stratification in the northern BoB inhibits the entrainment of the cooler-nutrient-rich subsurface waters to the surface during the event of dome formation. Consequently, the mixed-layer temperature in the NBoB region stays above the temperature criteria for active convection (>28 oC). Further, the inhibition of entrainment of nutrients causes the NBD region to be lower in productivity than the SLD region, as seen in chlorophyll distribution. We compare the NBD's heat and nutrient budget with the SLD and show that the near-surface stratification differences make the two domes distinct from each other.
Climate services for winter tourism in Romanian mountains
Authors: Bojariu Roxana , Velea Liliana , Irimescu Anisoara , Craciunescu Vasile , Puiu Silvia
Published: March 2021

WeCTOU (http://wectou.meteoromania.ro/) which delivers climate and environmental information tailored for tourism at 160 locations in Romania is a provider of climate services developed and operated by National Meteorological Administration.  European Commission and the European Centre for Medium-Range Weather Forecasts (ECMWF) through the Copernicus Climate Change Service (C3S) have provided the financial support. WeCTOU aims to extend its climate services and in this context, we have taken into account the needs of stakeholders interested in winter tourism in Romanian mountains using observations from national meteorological network together with reanalysis and model products extracted from the Climate Data Store developed at the ECMWF. Stakeholders interested in winter tourism in Romanian mountains span a wide range of categories from central and local administration to representatives of hospitality industry and individuals. In 2019, the Romanian Ministry of Economy, Energy and Business Environment, also responsible of tourism certified 195 ski slopes located in 20 Romanian counties. We use the ensemble distribution of number of days with snow depth larger than 30 cm from future projections covering the period 2021-2040 under climate change scenarios to provide a first guess assessment of future profitability of Romanian ski resorts compared with the reference period 1976-2005. This type of indicator together with climate products related to snow making are important for identifying opportunities for future investments in winter tourism. They are also important in general urban planning for localities which have to change their profile from winter resort to one which serve guests year-round.  Especially for tourists and hospitality industry, we use future projections of indicators relative to present conditions (2021-2040 vs. 1976-2005) such as the ensemble distribution of number of days with snow layers having depths larger than 30 cm during winter holidays (22 Dec- 04 Jan). Also, we have shown how testing all these winter climate services with the interested stakeholders has guided us during the incremental developing stages to shape the final design.   
Driving factors of the growth of US wind power generation - A decomposition of historical on-shore wind power generation data
Authors: Regner Peter , Gruber Katharina , Wehrle Sebastian , Schmidt Johannes
Published: March 2021

US Wind power generation has grown significantly over the last decades, driven by more and larger turbines being installed. However, less is known about how other factors affect the expansion of wind power. In this study, we use historical wind power generation time series, data on installed wind turbines and wind speed time series from the ERA5 data set to quantify driving factors of the growth of US wind power generation. By use of index-decomposition techniques and a regression analysis, we show how different factors affect the output of wind power generation in the US. These include changes in the number of installed turbines, average swept area, park efficiency, location choice, and hub height. Based on this, we discuss potential consequences for the future expansion of wind energy. As expected, the total rotor swept area is responsible for the largest part of the increase in generated power, due to a larger number of installed turbines and larger rotor sizes in particular. Unexpectedly, turbine efficiency slightly declined in the last decades. Wind speeds available to wind turbines have slightly increased. This is a result of larger hub heights, but also of new wind turbines being installed at windier locations.
The impact of London on a low-level jet
Authors: Tsiringakis Aristofanis , Theeuwes Natalie , Barlow Janet , Steeneveld Gert-Jan
Published: March 2021

The low-level jet (LLJ) is an important phenomenon that can affect (and is affected by) the turbulence in the nocturnal urban boundary layer (UBL). We investigate the interaction of a regional LLJ with the UBL during a 2-day period over London. Observations from two Doppler Lidars and two numerical weather prediction models (Weather Research & Forecasting model and UKV Met Office Unified Model) are used to compared the LLJ characteristics (height, speed and fall-off) between a urban (London) and a rural (Chilbolton) site. We find that LLJs are elevated (70m) over London, due to the deeper UBL, an effect of the increased vertical mixing over the urban area and the difference in the topography between the two sites. Wind speed and fall-off are slightly reduced with respect to the rural LLJ. The effects of the urban area and the surrounding topography on the LLJ characteristics over London are isolated through idealized sensitivity experiments. We find that topography strongly affects the LLJ characteristics (height, falloff, and speed), but there is still a substantial urban influence.
The impact of nanoplastic on embryonic development of Antarctic krill in current and future acidified conditions of the Southern Ocean 
Authors: Rowlands Emily , Galloway Tamara , Cole Matthew , Lewis Ceri , Peck Victoria , Thorpe Sally , Manno Clara
Published: March 2021

Antarctic krill (Euphausia superba), hereafter krill, are pivotal to the Antarctic marine ecosystem, forming the base of a highly productive system and contributing significantly to the biogeochemical cycle. The negative effects of anthropogenic climate stressors amplified in the Southern Ocean such as rapid warming and ocean acidification (OA) have been acknowledged for krill. Less explored is the impact of increasing plastic pollution, particularly in conditions that reflect the likely future Southern Ocean environment. We hypothesise that krill have heightened vulnerability to multi-stressor scenarios due to their physiological and behavioural traits coupled with rapid environmental changes of their Antarctic habitats. Here, we investigate the single and combined effects of nanoplastic (NP; spherical, aminated (NP-NH2), yellow-green, fluorescent polystyrene nanoparticles) and OA (pCO2-manipulated seawater, pH 7.7) on the embryonic development of krill eggs. Krill were collected in the Scotia Sea within the Atlantic sector of the Southern Ocean in austral summer 2019. Eggs from a single female were incubated in seawater at 0.5 °C for 6 days with three treatments: (i) with 0.16 μm NP, (ii) in acidified conditions, and (iii) with a combined treatment of NP (0.16μm) and acidification. All NP treatments were at a concentration of 2.5μg/ml. We found that exposure to the NP-OA multi-stress treatment negatively impacted the development of embryos, decreasing the probability of reaching the limb bud stage by 9% compared with the control, whilst no significant difference was observed for the singular NP or OA treatments. This preliminary study supports our hypothesis regarding the potential impacts of multiple stressors on vulnerable embryonic stages of this ecologically critical Antarctic species.
Drone-based sea ice albedo measurements and photogrammetry during the Arctic freeze-up in the MOSAiC expedition
Authors: Pirazzini Roberta , Hannula Henna-Reetta , Brus David , Dadic Ruzica , Scnheebeli Martin
Published: March 2021

Aerial albedo measurements and detailed surface topography of sea ice are needed to characterize the distribution of the various surface types (melt ponds of different depth and size, ice of different thicknesses, leads, ridges) and to determine how they contribute to the areal-averaged albedo on different horizontal scales. These measurements represent the bridge between the albedo measured from surface-based platforms, which typically have metre-to-tens-of-meters footprint, and satellite observations or large-grid model outputs.

Two drones were operated in synergy to measure the albedo and map the surface topography of the sea ice during the leg 5 of the MOSAiC expedition (August-September 2020), when concurrent albedo and surface roughness measurements were collected using surface-based instruments. The drone SPECTRA was equipped with paired Kipp and Zonen CM4 pyranometers measuring broadband albedo and paired Ocean Optics STS VIS (350 – 800 nm) and NIR (650-1100 nm) micro-radiometers measuring visible and near-infrared spectral albedo, and the drone Mavic 2 Pro was equipped with camera to perform photography mapping of the area measured by the SPECTRA drone.

Here we illustrate the collected data, which show a drastic change in sea ice albedo during the observing period, from the initial melting state to the freezing and snow accumulation state, and demonstrate how this change is related to the evolution of the different surface features, melt ponds and leads above all. From the data analysis we can conclude that the 30m albedo is not significantly affected by the individual surface features and, therefore, it is potentially representative of the sea ice albedo in satellite footprint and model grid areas.

The Digital Elevation Models (DEMs) of the sea ice surface obtained from UAV photogrammetry are combined with the DEMs based on Structure From Motion technique that apply photos manually taken close to the surface. This will enable us to derive the surface roughness from sub-millimeter to meter scales, which is critical to interpret the observed albedo and to develop correction methods to eliminate the artefacts caused by shadows.

The UAV-based albedo and surface roughness are highly complementary also to analogous helicopter-based observations, and will be relevant for the interpretation of all the physical and biochemical processes observed at and near the sea ice surface during the transition from melting to freezing and growing.
Investigations of DInSAR derived grounding line migration in Antarctica induced by ocean tides
Authors: Ip Yin Ying , Krieger Lukas , Floricioiu Dana
Published: March 2021

The migration of the glacier grounding line, the boundary between grounded ice and floating ice, is an important indicator of tice sheet stability in a warming climate. Ice-shelf thinning induces grounding line retreat, and potentially leads to the collapse of the inland catchment areas in centennial time periods. Therefore, a continuous observation of the grounding line position is of interest for ice sheet modelling also to predict future sea level rise. However, grounding line in nature is not static in position and it is subject to short-term fluctuations which are influenced by changes in ocean tide level and atmospheric pressure. Investigating tidal influence to the grounding line helps separating the tidal signal from the long-term migration because of ice shelf thinning. Also, it helps quantifying ice discharge and ice flow, as well as potential melting underneath the ice, due to intrusion of sea water.

In this study, the correlation between the time series of grounding line, derived from Sentinel-1 double difference interferograms and the ocean tide level computed from CATS2008 tide model and air pressure corrected with NCEP reanalysis data  are investigated. Study regions are chosen at the Filchner-Ronne Ice Shelf, the Amery Ice Shelf and Dronning Maud Land based on the availability of coherent interferograms and the large tidal amplitude at these locations. The result is expected to be presented as qualitative description of changes in the fringe belt pattern in double difference interferograms and statistical analysis of the derived changes in grounding line position, depending on the complexity of the grounding line structure and the topography of the bed rock.
The 38 years of the microclimate change dynamics across a cropland-windbreak-desert transition zone in the Ulan Buh Desert, northern China
Authors: Wang Guan , Luo Fengmin , Xin Zhiming , Li Junran , Xiao Huijie
Published: March 2021

The windbreak system is a major component of successful agricultural systems in arid deserts throughout the world. Ulan Buh Desert is one of the eight biggest deserts in China, and the oases there offer residence and cropland for over 90% of the local residents. However, due to climate change and human disturbances, the Ulan Buh Desert continues spreading to the south, bringing more pressure on the windbreak systems there. Meanwhile, the Chinese government put much effort into greening the desert, establishing artificial shrubs to prevent dune movement and soil loss. How microclimate in the cropland-windbreak-desert system responded to human activities and climate change has rarely been studied. In this study, we investigated the microclimate change dynamics across the cropland-windbreak-desert transition zone during the past 38 years. Two 50 m climatological towers, located in the same distance inner and outside a shelterbelt, have continuously monitored climatic factors, including air temperature, soil temperature, relative humidity, precipitation, evaporation, layered wind speeds, etc., and aeolian erosion related factors, such as layered dustfall. The long-time fluctuations of the inside and outside climatic factors have been analyzed, and the global climate change data, local land-use history, as well as the record of afforestation activities implemented by government and local people, were also collected. The results revealed that both the inside and outside windbreak air temperatures and soil temperatures increased during the past 38 years, which agrees with the global warming phenomenon. The inner windbreak air temperature is consistently lower than the outer windbreak areas, and the temperature difference is biggest in summer and smallest in winter. However, the soil temperature difference between the outside and inner windbreak is unstable. In 1995, 2002, and 2004, the dune areas even had lower soil temperature than the inner cropland. The precipitation is 0.5~100.7mm higher in cropland and the evaporation is lower in cropland when comparing to outside dune areas, but their annual variations changed greatly. The wind speed and erosion rate are significantly lower in cropland than desert dune areas, and the seasonal change exhibited a bimodal curve pattern. The results suggest that the cropland-windbreak-desert transition zone responded to global climate change simultaneously. Although the shelterbelt still creates a favorable regional climatic condition for the cropland, the differences between the inner and outer windbreak areas narrowed during the past 10 years. The aeolian erosion rate reduced significantly in outside windbreak dune areas, which may largely attribute to the artificial Haloxylon ammodendron communities planted at the southeastern margin of the desert.
WeatherBench Probability: Medium-range weather forecasts with probabilistic machine learning methods.
Authors: Garg Sagar , Rasp Stephan , Thuerey Nils
Published: March 2021

Because the atmosphere is inherently chaotic, probabilistic weather forecasts are crucial to provide reliable information. In this work, we present an extension to the WeatherBench, a benchmark dataset for medium-range, data-driven weather prediction, which was originally designed for deterministic forecasts. We add a set of commonly used probabilistic verification metrics: the spread-skill ratio, the continuous ranked probability score (CRPS) and rank histograms. Further, we compute baseline scores from the operational IFS ensemble forecast. 

Then, we compare three different methods of creating probabilistic neural network forecasts: first, using Monte-Carlo dropout during inference with a range of dropout rates; second, parametric forecasts, which optimize for the CRPS; and third, categorical forecasts, in which the probability of occurrence for specific bins is predicted. We show that plain Monto-Carlo dropout does not provide enough spread. The parametric and categorical networks, on the other hand, provide reliable forecasts, with the categorical method being more versatile.
Soil Augmentation by Humus: Replenishing lost soils and supplementing new ones
Authors: Bagla Hemlata , Khan Asma
Published: March 2021

Earth’s regolith consists of a vital component that is lacking on other planets ­­– the pedosphere or soil body – that is rich in organic matter, soil fauna, minerals, water, gases, that together support life and is thus essential for plant growth. In stark contrast to our blue planet, Martian regolith is devoid of organic matter and contains crushed volcanic rocks, with high mineral content and toxic chemicals like perchlorates. Nevertheless, Martian and Lunar regolith simulants formulated by NASA, have been experimented for crop growth by addition of organic matter suitable to bind xenobiotics and provide ample nutrients, as an essential step towards expanding our horizon in the extensive field of soil sciences.

Soil is an ecosystem as a whole and acts as a modifier of planet Earth’s atmosphere. The organic matter present in it originates mainly from plant metabolites with the onset of senescence and humification. Humic substances thus formed in the pedosphere exhibit exceptional characteristics for soil conditioning. Besides providing nutrients and aeration to the soil, they interact and bind with toxic heavy metals, radionuclides, pesticides, industrial dyes, and other xenobiotics that may be present as pollutants in the ecosystem, thus acting as natural sieves. As top soils have maximum organic matter, essential for plant growth, phenomenon like soil erosion leave the soils devoid of humic substances. Another major reason for soil degradation is excessive salinity, leading to osmotic and ionic stress in plants, eventually reducing their growth. Addition of humic acid in soils provides protection against high saline stress and minimizes yield losses. In India, one of the leading agrarian countries, it is a common practice to enrich soils with manure, which is an inexpensive form of humus-boost for the crops. Such practices aid the cyclic flow of organic matter in the environment, against the background of widespread soil degradation.

Another global form of soil degradation is radioactive contamination of soils which occurs mainly due to nuclear accidents and improper practices of radioactive waste disposal. In order to explore such interactions with humic acid following Green technique, batch biosorption studies were performed over a range of parameters, with radionuclides Cs and Sr that are found in low level radioactive wastes. Biosorption percentages of 91±2% and 84±1% were obtained for Cs and Sr respectively. The technique is chemical-free and emphasizes the ‘nature for nature’ outlook of solving environmental problems. Humic acid and its various forms thus act as traps for radionuclides and work as excellent restorative soil stimulants that supplement depleted soils, boost plant growth, and play a vital role in sustaining life on Earth.
Remediation-related monitoring of heavy metal concentration of contaminated Technosol using hyperspectral measurements
Authors: Kaestner Friederike , Sut-Lohmann Magdalena , Raab Thomas , Feilhauer Hannes , Chabrillat Sabine
Published: March 2021

Across Europe there are 2.5 million potentially contaminated sites, approximately one third have already been identified and around 15% have been sanitized. Phytoremediation is a well-established technique to tackle this problem and to rehabilitate soil. However, remediation methods, such as biological treatments with microorganisms or phytoremediation with trees, are still relatively time consuming. A fast monitoring of changes in heavy metal content over time in contaminated soils with hyperspectral spectroscopy is one of the first key factors to improve and control existing bioremediation methods.

At former sewage farms near Ragow (Brandenburg, Germany), 110 soil samples with different contamination levels were taken at a depth between 15-20 cm. These samples were prepared for hyperspectral measurements using the HySpex system under laboratory conditions, combing a VNIR (400-1000 nm) and a SWIR (1000-2500 nm) line-scan detector. Different spectral pre-processing methods, including continuum removal, first and second derivatives, standard normal variate, normalisation and multiplicative scatter correction, with two established estimation models such as Partial Least Squares Regression (PLSR) and Random Forest Regression (RFR), were applied to predict the heavy metal concentration (Ba, Ni, Cr, Cu) of this specific Technosol. The coefficient of determination (R2) shows for Ba and Ni values between 0.50 (RMSE: 9%) and 0.61 (RMSE: 6%) for the PLSR and between 0.84 (RMSE: 0.03%) and 0.91 (RMSE: 0.02%) for the RFR model. The results for Cu and Cr show values between 0.57 (RMSE: 17.9%) and 0.69 (RMSE: 15%) for the PLSR and 0.86 (0.12%) and 0.93 (0.01%) for the RFR model. The pre-processing method, which improve the robustness and performance of both models best, is multiplicative scatter correction followed by the standard normal variate for the first and second derivatives. Random Forest in a first approach seems to deliver better modeling performances. Still, the pronounced differences between PLSR and RFR fits indicate a strong dependence of the results on the respective modelling technique. This effect is subject to further investigation and will be addressed in the upcoming analysis steps.
Improving the decision-making in DICE: self-adaptive climate policies to handle explicit uncertainty and adaptation modelling
Authors: Carlino Angelo , Tavoni Massimo , Castelletti Andrea
Published: March 2021

DICE (Dynamic Integrated Climate Economy) and other cost-benefit integrated assessment models are used to study the economically optimal climate policy or to evaluate economic performance of alternative policies, such as 2°C compliant emission trajectories.

Recently, DICE has been updated to provide economically optimal climate policies keeping global warming in line with the Paris Agreement. Yet, explicit uncertainty and adaptation modelling are still overlooked. Introducing these components requires a transition from the traditional perfect-foresight static decision-making framework to a dynamic one, able to change strategy in order to react to the realization of uncertainties.

In this work, starting from the updates proposed by Hansel et al. (2020), we present an updated DICE model that: i) explicitly represents adaptation in the form of temporary and long-term adaptation investment; ii) explicitly describes stochastic, parametric and structural uncertainty over the physical and socio-economic components of the model including adaptation efficiency and climate damages specification; iii) leverages self-adaptive control policies to implement a more realistic decision-making scheme that allows to adjust climate policy after that new information arises.

Results show that the self-adaptive policies allow for a reduction in the discrepancy between economically optimal climate policy and the 2°C temperature target set with the Paris Agreement, which resurfaces when introducing adaptation, also in presence of uncertainty. When using self-adaptive policies, average adaptation costs remain low and, thanks to the ability to modulate adaptation choices depending on the scenario eventually unfolding, also climate damages are maintained at a low level. As a result, more economic resources are made available for mitigation in the short-term resulting in a reduced temperature increase in 2100 for a same level of welfare.
Analysing the cost-effectiveness of early action for food security through forecasting shortages in maize calories; a case study for Ethiopia 
Authors: Emeis Amber , Guimarães Nobre Gabriele , van den Homberg Marc , Teklesadik Aklilu , Boult Vicky
Published: March 2021

The Ethiopian agricultural system is predominantly formed by smallholder and rainfed farmers. Their local food systems are greatly reliant on seasonal climate variability. Often, droughts and food insecurity are interlinked and can negatively impact local communities. In addition to climate variability, a number of socio-economic factors such as multiple harvest failures, distance to markets and pre-existing inequalities are well known to impact people’s access to safe, sufficient and affordable food. Anticipatory action to avoid a situation of food security crisis often requires the understanding of how many people can be potentially affected by a shock and how much financing should be invested. 

This study aims to forecast shortages in maize calories, which is defined as the percentage of the population for which not sufficient maize calories are available. Forecast models were developed for agricultural and agro-pastoral livelihood zones in Ethiopia in connection to the unimodal and bimodal rain seasons by using the Fast-and-Frugal Trees Algorithm. To forecast shortage events, five variables were used ranging from socio-economic to physical drivers: 1) soil moisture (Tropical Applications of Meteorology using Satellite data and ground-based observations (TAMSAT)), 2) maize production from the previous season, 3) the Gini index, 4) the main livelihood mode and 5) the travel time to the closest market. The lead time of the model is increased using TAMSAT forecast data to create a wider window for action before harvesting. 

The skill of the model with increased lead-time in relation to the cost of the humanitarian intervention was analysed to examine the cost-effectiveness of forecast-based action. Therefore, the cost of acting early (through a scheme of cash transfer) has been compared to ex-post interventions. To assess the cost-effectiveness of the cash transfer, the prices of a basket of goods before and after harvesting are included in the model with the assumption that prices of staple crops increase when there is scarcity (food insecurity). With these results, the study will explore the practicality of implementing the anticipatory action by looking at the implications of model uncertainty (False Alarms, ‘acting in vain’). Likewise, the possible opportunities and challenges in regards to operationalizing the model will be deliberated. Accordingly, this study hopes to contribute to the use of early warning early action systems by humanitarian agencies in reducing the impacts of natural hazards. 
Dense avalanches hitting structures: demarcating depth-dependent impact pressures from velocity-squared impact pressures
Authors: Faug Thierry
Published: March 2021

Predicting the magnitude of the impact force that snow avalanches can exert on structures still remains a challenging question.

In fast flow regimes, the impact pressure is mainly driven by the kinetic energy of the flow: it scales as one-half the product of the flow density and the square of the avalanche speed, and the effect of the shape of the structure is encapsulated in the so-called drag coefficient. Recent measurements on well-documented snow avalanches that have impacted different types of structures have confirmed the existence of another impact force regime at lower speed for which the pressure exerted on the obstacle is independent of the avalanche speed but rather controlled by the lithostatic pressure associated with the typical flow thickness. These measurements have also shown that the depth-dependent force could reach values that are many times greater than the lithostatic force.

The present paper proposes a general analytic form for the impact force of dense avalanches on structures. The approach is based on the application of mass and momentum conservation equations, in their depth-averaged forms, to a control-volume which surrounds the influence zone of the obstacle. A criterion to distinguish between the depth-dependent force regime and the velocity-square force regime can be derived. It is demonstrated that the size of the influence zone of the obstacle, relative to the dimension of the obstacle and/or the avalanche thickness, is a key ingredient (in addition to the traditional Froude number) to demarcate the depth-dependent impact forces from the velocity-square impact forces. Further developments are needed to unravel the size and shape of the influence zone (of any kind obstacle for any type of flowing snow), and then to be able to hone the proposed criterion. However, the present study takes a step forward for a better characterization of avalanche impact forces on structures.
Young solar wind coherent structures from inertial to sub-ion range
Authors: Vinogradov Alexander , Alexandrova Olga , Artemyev Anton , Maksimovic Milan , Alexei Vasiliev , Petrukovich Anatoly , Bale Stuart , Issautier Karine , Moncuquet Michel
Published: March 2021

We study intermittency of turbulence in the young solar wind at 0.17 au with NASA/Parker Solar Probe during the first perihelion. We use a merged FIELDS/Search Coil and Fluxgate Magnetometers data for magnetic field, SWEAP/SPC instrument for ions and RFS/FIELDS quasi thermal noise data for electrons to characterize the plasma environment. The merged magnetic waveforms have 3.4 ms time resolution, which allows us to resolve a wide range of scales, going from MHD inertial range to sub-ion range. We apply a wavelet transform to the magnetic waveforms and we observe localized enhancements in power density that form corresponding peaks in Local Intermittency Measure (LIM) going from MHD to kinetic scales. These LIM peaks are not present in the random-phase signal with the same Fourier amplitudes. This indicates the presence of coherent structures in the observed signal. To detect coherent structures at a given timescale, we use the maximum of the random-phase signal LIM at the same scale as a threshold. We observe a variety of coherent events from MHD to kinetic scales. We estimate the filling factor of the structures as well as their minimum variance properties and local topology. The physical connections between intermittency and solar wind heating are discussed.
Impact of compound weather extremes on winter wheat in Germany
Authors: Ellsäßer Florian , Xoplaki Elena , Behr Lorine , Luterbacher Juerg , Toreti Andrea , Zampieri Matteo
Published: March 2021

In the last decades, Europe has experienced an increase in the occurrence of extreme spring-to-summer heat and rainfall deficit. The compound impact of both hazardous weather events causes extreme drought conditions, which are likely to increase in frequency in the coming decades, with large impacts on agriculture and crop productivity. In this study, we analyze and attribute the effects of compound weather extremes on yield anomalies in Germany from 1989 to 2019.

To characterize the impact of compound events on irrigated and rainfed crops, statistical index-based approaches have widely been used, linking historic weather aggregates to yield records. To analyze and predict the impact of compound extreme events on crop yield, productivity and cultivation area at subnational level for Germany, we merged available yield data from multiple sources to create a consistent yield record of the last 30 years at county level. We then calculated indices on gridded meteorological data and records of phenological crop phases and agricultural practices, covering three decades, to analyze the effect of compound weather extremes on winter wheat yield.

We evaluated the SPEI (Standardized Precipitation Evaporation Index) for the 6-month period before winter wheat is harvested, to account for extremes in excess and lack of water availability. We further calculated the HMD (Heat Magnitude Day) index for the 3-month period before harvest, to assess the impact of heat stress conditions. Finally, a composite indicator the CSI (Combined Stress Index), based on a linear superposition of the standardized HMD and SPEI, is applied. The CSI is calibrated to local conditions by determination of coefficients that maximize the explanatory power of the index, using a bilinear ridge regression and county level yield observations.

The results of this study help to better understand the impacts of compound extremes on winter wheat in Germany and reveal regions that are especially threatened by yield losses from compound weather extremes.
Role of eddies and N2 fixation in shaping C:N:P proportions in the Bay of Bengal during spring
Authors: Sahoo Deepika , Saxena Himanshu , Nazirahmed Sipai , Kumar Sanjeev , Sudheer Athiyarath , Bhushan Ravi , Sahay Arvind , Singh Arvind
Published: March 2021

Bioavailable nitrogen (N) and phosphorus (P) determine the strength of the ocean’s carbon (C) uptake and variation in their ratio (N:P) is key to phytoplankton growth. A similarity between C:N:P ratio (106:16:1) in plankton and deep-water inorganic nutrients was observed by Alfred C. Redfield, who suggested that biological processes in the surface ocean controlled deep ocean chemistry. Recent studies suggest that the ratio varies geographically. The veracity in C:N:P ratio could be attributed to the characteristic physical and biogeochemical processes, which play an important role in regulating the elemental dynamics in ocean. Basins like the northern Indian Ocean due to its geographic setting and monsoonal wind forcing provide a natural laboratory to explore the role of environmental factors, physical and biogeochemical processes on C:N:P stoichiometry.

We sampled the Bay of Bengal for its C, N, and P contents in the organic and inorganic pool from surface to 2000 m at 8 stations (5 coastal, 3 open ocean) during spring 2019. Mesoscale anticyclonic eddies were identified in our sampling area, which were associated with low nutrient concentrations in the photic depth. Mean (NO3- + NO2-):PO43- ratio was 0.6 at eddy and 4.7 at non eddy stations. On the other hand, C:N:P in the organic matter was same at eddy and non-eddy locations. Mean C:N:P ratio in particulate organic matter was 254:39:1 and 244:37:1 in the photic depth of the coastal and open ocean stations, respectively. Biological N2 fixation contributed ~0.1-0.4% to the N:P ratio of export flux, which ultimately contributes to the (NO3- + NO2-):PO43- ratio in subsurface waters. Our results highlight the importance of physical and biological processes in changing elemental stoichiometry.