bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of fluvial sediment yields in hyper-arid areas, exemplified by Nahal Nehushtan, Israel 
Authors: Armoza-Zvuloni Rachel , Shlomi Yanai , Abadi Itay , Shem-Tov Rachamim , Laronne Jonathan B.
Published: March 2021

Floods rarely occur in hyper-arid deserts and little is known about the magnitude and frequency of sediment delivery from their basins, despite their importance to changes to the landscape as well as to infrastructures and engineering activities. Sediment yield from the Nahal Nehushtan watershed (15.7 km2) located in the Timna Valley in southern Israel, was determined by assessing stratigraphic sections in its 60-year reservoir deposits. Stratigraphic correlation between event couplets allowed quantification of sediment yields representing 13 former flash-flood events. Based on the sediment volume in the reservoir, the 24.6 t km-2 y-1 average sediment yield is the lowest among other studied warm deserts. Among the event layers, five are voluminously small and seven are medium-sized. The thickest layer, deposited by a flash flood caused by a single short rain event, contributed 29% of the total sediment yield. This demonstrates the overarching effect of medium magnitude events on the rate of sediment production in a hyper-arid setting. Based on event reservoir sedimentation from watersheds located in several hyper-arid areas in the Middle East and North America, sediment load increases with drainage area as expected; however, sediment yield does not decrease with drainage area, as was shown for arid environments. Overall, mean annual sediment yield is very low and increases with flood frequency, with considerable variation generated by local characteristics. Our quantitative results together with previous studies of hyper-arid areas, provide complementary evidence of fluvial sediment transport - the main landscape designer in fluvial desert landscapes.
Measuring changes in snowpack SWE continuously on a landscape scale using lake water pressure 
Authors: Pritchard Hamish , Farinotti Daniel , Colwell Steven
Published: March 2021

The seasonal snowpack is a globally important water resource that is notoriously difficult to measure. Existing instruments make measurements of falling or accumulating snow water equivalent (SWE) that are susceptible to bias, and most can represent only a point in the landscape. Furthermore the global array of SWE sensors is too sparse and too poorly distributed to be an adequate constraint on snow in weather and climate models. We present a new approach to monitoring snowpack SWE from time series of lake water pressure. We tested our method in the lowland Finnish Arctic and in an alpine valley and high-mountain cirque in Switzerland, and found that we could measure changes in SWE and their uncertainty through snowfalls with little bias and with an uncertainty comparable to or better than that achievable by other instruments. More importantly, our method inherently senses change over the whole lake surface which can be several square kilometres, or hundreds of million of times larger than the aperture of a pluviometer. This large scale makes our measurements directly comparable to the grid cells of weather and climate models. We find, for example, snowfall biases of up to 100% in operational forecast models AROME-Arctic and COSMO-1. Seasonally-frozen lakes are widely distributed at high latitudes and are particularly common in mountain ranges, hence our new method is particularly well suited to the widespread, autonomous monitoring of snow-water resources in remote areas that are largely unmonitored today. This is potentially transformative in reducing uncertainty in regional precipitation and runoff in seasonally-cold climates.
Rare Earth Elements as geochemical tracers of paleoenvironments in tropical montane peat, Western Ghats, India
Authors: Ramya Bala Prabhakaran , Le Roux Gaël , De Vleeschouwer Francois , Sukumar Raman , Krishnan Sajeev
Published: March 2021

Mineral dust, especially from the Middle-East, has been known to affect monsoon circulation in India, a country whose economy is heavily contingent on the timely arrival of the monsoon. Reconstruction of dust circulation in the past and its relationship to the monsoon has never been attempted in India although inorganic geochemical proxies from peat have been used in various parts of the world. Finding suitable peat archives to use inorganic geochemical proxies in the largely tropical and sub-tropical Indian environments is a challenge. Montane peat in the Sandynallah valley in the southern Western Ghats, peninsular India, is one of the oldest in the world (>50 ka) and has been shown to record continuous climatic and vegetation changes of at least 30,000 yrs of the past. We explored the usefulness of inorganic geochemical proxies for the first time here to reconstruct dust circulation. Inorganic geochemical analysis was carried out on acid digested peat samples analyzed using Inductively Coupled Plasma-Mass Spectrometry and Optical Emission Spectroscopy at EcoLab, Toulouse. We see that the major (e.g., Al, Fe, Mn, K, Na, Mg, Ca) and commonly used trace (Cu, Zn, Pb) elements do not show many significant trends for paleoenvironmental interpretation. Preliminary analyses indicate that lithogenic elements Ti and Zr have high correlation through time. In this study, we used scaled Rare Earth Element (REE) concentrations and Zr as a reference to calculate enrichment factors (REE EFs) and found that the Lanthanide series showed promise for identifying potential sources of atmospheric dust. We find strong enrichments in some sections of the last glacial (the strongest enrichment is observed at ~30 ka), indicative of environmental conditions that supported increased dust input, possibly related to the higher dust circulations in the glacial periods as evidenced by ice core studies. We report for the first time inorganic geochemical proxies from peat in India and propose that the lanthanide group could be established as a useful proxy for atmospheric dust sources in tropical montane peat.
Inferring saline tracer transport characteristics from time-lapse GPR experiments
Authors: Giertzuch Peter-Lasse , Shakas Alexis , Brixel Bernard , Doetsch Joseph , Jalali Mohammadreza , Maurer Hansruedi
Published: March 2021

Monitoring and characterization of flow and transport processes in the subsurface has been a key focus of hydrogeological research for several decades. Such processes can be relevant for numerous applications, such as hydrocarbon and geothermal reservoir characterization and monitoring, risk assessment of soil contaminants, or nuclear waste disposal strategies.

Monitoring of flow and transport processes in the subsurface is often challenging, as they are usually not directly observable. Here, we present an approach to monitor saline tracer migration through a weakly fractured crystalline rock mass by means of Ground Penetrating Radar (GPR), and we evaluate the data quantitatively in terms of a flow velocity field and localized difference GPR breakthrough curves (DRBTC).

Two comparable and repeated tracer injection experiments were performed within saturated rock on the decameter scale. Time-lapse single-hole reflection data were acquired from two different boreholes during these experiments using unshielded and omnidirectional borehole antennas. The individual surveys were analyzed by difference imaging techniques, which allowed ultimately for tracer breakthrough monitoring at different locations in the subsurface. By combining the two complimentary GPR data sets, the 3D tracer velocity field could be reconstructed.

Our DRBTCs agree well with measured BTCs of the saline tracer at different electrical conductivity monitoring positions. Additionally, we were able to calculate a DRBTC for a location not previously monitored with borehole sensors. The reconstructed velocity field is in good agreement with previous studies on dye tracer data at the same research locations. Furthermore, we were able to resolve separate flow paths towards different monitoring locations, which could not be inferred from the electrical conductivity sensor data alone. The GPR data thus helped to disentangle the complex flow field through the fractured rock.

Out technique can be adapted to other use cases such as 3D monitoring of fluid migration (and thus permeability enhancement) during hydraulic stimulation and tracing fluid contaminants – e.g. for nuclear waste repository monitoring.
New management perspectives in pressurized on-demand irrigation systems using innovative smart control valves
Authors: Ferrarese Giacomo , Pagano Alessandro , Malavasi Stefano , Fratino Umberto
Published: March 2021

Irrigated agriculture is currently one of the most water-consuming human activities at global level. Furthermore, in the next years, water demand for irrigation is expected to increase within a challenging framework characterized by the effects of climate change and dynamics such as the population increase. In this context and considering that up to now irrigation networks have experienced a limited access to innovation (such as e.g., several areas of the Mediterranean region, above all in the North African side), the opportunities offered by digitalization could be crucial in the next future. New technologies and IoT solutions can effectively improve the management of limited resources and the quality of service to users. In the present work, the advances in management of the irrigation networks that can be reached using a smart control valve, the GreenValveSystem (GVS), are discussed. The GVS is an innovative electro actuated control valve able to harvest part of the energy of the flow to enable high frequency monitoring of pressures and flow rate and real time operation on the valve, without the necessity of external power supply. It has been, up to now, positively tested and adopted in drinking water supply systems. A model of an on-demand pressurized irrigation network is used to provide, through hydraulic simulations, a proof-of-concept of the potential of such devices to support the selection and implementation of specific management strategies to limit (or even avoid) the occurrence of hydrant failures (i.e. an insufficient pressure or discharge ), and to guarantee an effective and sustainable use of water resources. In the study a procedure to find the best placement of the GVSs and some basilar management rules that limit failures is showed. This preliminary study demonstrates some of the improvement that the use of innovative devices based on IoT concepts, like cloud management of data and remote operations, can bring to water agencies and users.
Does CMIP6 better constrain projections of 21st century Antarctic sea ice loss?
Authors: Holmes Caroline , Bracegirdle Tom , Holland Paul
Published: March 2021

Results from CMIP5 have previously suggested that ensemble regression techniques or model selection may provide solutions to the challenge of making projections of future Antarctic sea ice area (SIA) in the presence of large historical biases. Here, we revisit and extend such analysis incorporating the CMIP6 ensemble, which shows modest improvements in some aspects of sea ice simulation and in particular a reduction of inter-model spread in historical SIA. We focus on the strongest forcing scenarios analysed, CMIP5 RCP85 and CMIP6 SSP5.85.

In summer (February) the historical climatology of SIA is a strong linear constraint on projections of SIA in both generations. This is because the strong forcing leads to the loss of the majority of summer SIA in each model, so that the models that start with greater SIA exhibit greater reductions. Differences between CMIP5 and CMIP6 are largely explained by the fact that, compared to CMIP6, CMIP5 contains many more models that have very large positive biases in historical SIA and do not lose the majority of ice.

In winter (September), a much smaller proportion of SIA is lost, but inter-model spread in SIA climatology still explains just under half the variance in projections of SIA change, in both CMIP5 and CMIP6. The mean historical winter climatology is similar between generations, as is the regression slope of SIA change against SIA climatology.  However, there is a greater reduction of SIA in CMIP6 than CMIP5. We find this to be statistically related to greater global mean warming in CMIP6 than CMIP5, and therefore potentially to the larger climate sensitivity in the CMIP6 ensemble.

These findings imply that, depending on season, a different balance of local (SIA climatology) and global (GMST change) drivers can be used to explain the inter-model and inter-generation spread in projections of SIA loss. They also firmly tie our ability to project Antarctic SIA loss to our understanding of the fidelity of higher CMIP6 climate sensitivity. Questions remain about whether models are correct in their simulation of Antarctic SIA sensitivity to global surface temperature.
Electrojet poleward boundary variations with IMF By and season
Authors: Walker Simon , Decotte Margot , Laundal Karl , Reistad Jone , Ohma Anders , Hatch Spencer
Published: March 2021

By utilising measurements from twenty ground magnetometer stations in Fennoscandia, divergence-free ionospheric currents above this region are modelled using spherical elementary currents (SECS). New modelling techniques are implemented that coerce the model to find a solution that resembles the resolvable ionospheric currents. The divergence-free currents are evaluated along the 105o magnetic meridian covering a period of almost 20 years with a resolution of 1 minute, as a result of the magnetometers chosen. From these sheet current density latitude profiles, the boundaries of the auroral electrojet are identified. After performing a large statistical analysis it is found that there is a significant IMF By effect on the poleward boundary of the electrojets during the Summer but not during the Winter. We suggest that this seasonal effect can be attributed to the effects of lobe reconnection on the extent of currents in the auroral electrojets. Further work is done to compare the SECS derived electrojet boundaries with particle precipitation data from low orbit satellites.
En-ROADS: A Global Energy and Climate Simulator to Support Strategic Thinking and Public Outreach
Authors: Kapmeier Florian , Sterman John , Siegel Lori , Eker Sibel , Fiddaman Tom , Homer Jack , Rooney-Varga Juliette , Jones Andrew
Published: March 2021

Integrated assessment models (IAMs) have advanced scientific understanding of mitigation pathways, yet most are not directly accessible to policymakers and other leaders. Here we describe En-ROADS, a publicly available, fully documented online policy simulation model designed to complement IAMs in public outreach. En-ROADS represents the energy-economy-climate system at a globally aggregated level. It has been carefully grounded in the best available science and is calibrated to fit historical data and projections from multiple IAMs across all SSP scenarios. Through an intuitive interface, users choose assumptions, policies, and actions to mitigate GHG emissions, receiving immediate feedback on likely energy, emissions, and climate pathways through 2100, enabling users to explore policies and uncertainties for themselves.

 

 
Estimating Gridded Domestic Water Demand and Assessing its Vulnerability over South-East Asian Countries
Authors: Panda Manas Ranjan , Kim Yeonjoo
Published: March 2021

During the past three decades, the over-growing population of the south-east Asian countries is becoming a threat to the available potential water sources. This region also includes many developed as well as developing countries including Korea, China, Japan and India, and the higher rate of GDP growth also enhanced the living standard of people. As a result, the water scarcity has been increasing in various mega-cities of the region. Here, we present the assessment of grid-scale domestic water demand of each country by evaluating the gridded Domestic Structural Water Intensity (DSWI) over a period of 1995-2015 at a spatial resolution of 0.5°. We estimated yearly grid-scale DSWI with using the past economic development based on GDP and the population. Considering the gridded water demand, we assessed the vulnerability of major river basins of the region and the few cities having more than one million population. A few mega-cities in India located in arid and semi-arid regions of the river basins are already experiencing water stress. Developing such gridded dataset will give a better shape to project the future water demand by integrating the datasets within a water demand module of any land surface models.

Acknowledgements

This work was supported by a grant from the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (2020R1A2C2007670).
Environmental drivers of planform change in the glacially-fed Rio Chubut, Argentina (42°S)
Authors: Skirrow Grace , Smedley Rachel , Chiverrell Richard , Hooke Janet
Published: March 2021

The eastern margin of the former Patagonian Ice Sheet was drained by large and dynamic river systems, which remain largely unstudied. New geomorphological mapping and luminescence chronology of the glacially-fed Rio Chubut reveal the preservation of large gravel outwash terraces up to 50 m above the modern river channel that previously acted as glacial spillways during the last glaciation. Also discovered is a gradual shift from a braided to a meandering planform between 12.3 ± 1.0 ka and 9.4 ± 0.8 ka, where the braided system experienced a decrease in energy and subsequent abandonment, transitioning into the meandering system that persists today. The coincidence of a new luminescence age from the innermost ice lobe in the Epuyen area (18.1 ± 2.2 ka), palaeoenvironmental records (Moreno et al. 2018, Whitlock et al. 2007, Iglesias et al. 2016) and the PATICE ice sheet reconstruction (Davies et al, 2020) suggest that the abandonment of the Rio Chubut braided planform was not a product of the river decoupling from the ice sheet. Alternatively, it was a response to the reduced water supply likely linked with the weakening and southward shift in the mid-latitude storm tracks and westerlies ~11.3 ka (Moreno et al. 2018). These findings contradict the widely reported process of planform change in glacially-fed river systems whereby a river decoupled from a glacier experiences a loss in sediment supply, which leads to incision and the river confining to a single channel. Here at the Rio Chubut, braiding is sustained in a paraglacial landscape for ~5 ka after the ice had retreated into the Andean mountains. A reduction in water supply related to precipitation changes in the early Holocene is identified as the key driver of planform change.

References

Davies, B.J., Darvill, C.M., Lovell, H., Bendle, J.M., Dowdeswell, J.A., Fabel, D., García, J.L., Geiger, A., Glasser, N.F., Gheorghiu, D.M. and Harrison, S., 2020. The evolution of the Patagonian Ice Sheet from 35 ka to the present day (PATICE). Earth-Science Reviews, p.103152.

Iglesias, V., Markgraf, V. and Whitlock, C., 2016. 17,000 years of vegetation, fire and climate change in the eastern foothills of the Andes (lat. 44 S). Palaeogeography, Palaeoclimatology, Palaeoecology, 457, pp.195-208.

Moreno, P.I., Videla, J., Valero-Garcés, B., Alloway, B.V. and Heusser, L.E., 2018. A continuous record of vegetation, fire-regime and climatic changes in northwestern Patagonia spanning the last 25,000 years. Quaternary Science Reviews, 198, pp.15-36.

Whitlock, C., Moreno, P.I. and Bartlein, P., 2007. Climatic controls of Holocene fire patterns in southern South America. Quaternary Research, 68(1), pp.28-36.
Macroplastic storage and remobilization in rivers
Authors: Liro Maciej , van Emmerik Tim , Wyżga Bartłomiej , Liro Justyna , Mikuś Paweł
Published: March 2021

Processes of macroplastic (plastic particles > 5 mm) storage and remobilization in rivers have been overlooked so far, but are of crucial importance for the estimation of plastic accumulation and transport and associated risks. We present a conceptual model that defines phases of the macroplastic route through a fluvial system and systematizes their main controls. We divided macroplastic route into (1) input, (2) transport, (3) storage, (4) remobilization and (5) output phases. Phase 1 is mainly controlled by humans, phases 2–4 by fluvial processes, and phase 5 by both types of controls. We hypothesize that natural characteristics of fluvial systems and their modification by dam reservoirs and flood embankments construction are key controls on macroplastic storage and remobilization in rivers. The zone of macroplastic storage can be defined as a river floodplain inundated since the beginning of widespread disposal of plastic waste to the environment in the 1960s and the remobilization zone as a part of the storage zone currently influenced by floodwaters and bank erosion. The amount of macroplastic in both zones can be estimated using data on the abundance of surface- and subsurface-stored macroplastic, and the lateral and vertical extent of the zones. A demonstrated diversity of factors controlling the route of macroplastic through a fluvial system requires a broader, transdisciplinary perspective including humans who not only dispose plastic, but are also affected by it both physically and aesthetically, and who may remove it from rivers.
Investigating the occurrence, likelihood and regional variability of extreme ozone pollution episodes across the UK
Authors: Gouldsbrough Lily , Hossaini Ryan , Eastoe Emma , Young Paul J.
Published: March 2021

Warm summer temperatures provide ideal conditions for the occurrence of extreme ground level ozone pollution episodes. Given the well-established negative impacts of ozone on human and plant health, understanding and attributing these extreme events is of importance to the scientific and wider community, particularly as heatwaves may become more frequent due to climate change. Extreme Value Analysis provides a powerful and flexible framework in which to statistically model unusually large observed values of ozone extracted from historical data. Here, a temperature dependent Peaks-Over-Threshold method based upon the Generalised Pareto Distribution is used to carry out a regional comparison of extreme ozone pollution episodes within the UK. Our analysis uses surface ozone observations from the UK’s extensive Automatic Urban and Rural Network. The statistical model was used to quantify the frequency and magnitude of extreme ozone events, including a probabilistic assessment of exceeding UK public health thresholds, conditional on temperature. Return levels are provided for each monitoring site demonstrating the expected future projections of extreme ozone pollution events across the UK. We find that across UK rural background sites, return periods for a daily maximum 8-hr ozone level of 100 ug/m3 (a 'moderate' level of air pollution in the UK's Air Quality Index) range from 32-147 days, based on analysis of the data in the decade 2010-2019. Similarly, for urban background sites the range is 36-869 days. An analysis of the spatio temporal variability in UK ozone extremes, along with their temperature dependence, will be presented.
What can we learn about small-scale spatial variability of surface ocean dimethylsulfide (DMS) concentrations from high frequency novel measurements?
Authors: Manville George , Halloran Paul , Bell Tom , Mulcahy Jane , Mahajan Anoop , Hulswar Shrivardhan , Simo Rafel , Gali Marti
Published: March 2021

Analysis of new high frequency dimethylsulfide (DMS) measurements indicates a latitudinal dependence to the patterns of small-scale variability; this points to previously unrecognised drivers of DMS spatial variability. DMS makes a significant contribution to natural marine aerosol. The amount and distribution of preindustrial DMS emissions is important for constraining the influence of anthropogenic aerosol on climate. The impact of variations in seawater DMS concentration on climatological (Lana et al. 2011) flux uncertainty is as large as the choice of gas transfer velocity parameterization. Improving understanding of the spatial variability of seawater DMS will help improve climatological flux estimates. High frequency data enables an assessment of the spatial variability lengthscale of DMS. We use 35 high frequency observational datasets, including measurements from the GSSDD (Global Surface Seawater DMS Database), NAAMES (North Atlantic Aerosol and Marine Ecosystem Study), and SCALE (Southern oCean SeAsonaL Experiment), to assess the variability lengthscale of DMS globally, and in all ocean basins at different stages of the seasonal cycle. We interpret our results within the context of ancillary physical and biogeochemical measurements, which may be potential drivers of the regional variability patterns of DMS concentrations.
Finite Element Method-based geomechanical risk assessment of underground laboratory located in the deep copper mine
Authors: Fulawka Krzysztof , Pytel Witold , Mertuszka Piotr , Szumny Marcin
Published: March 2021

Underground laboratories provide a unique environment for various industries and are a suitable place for developing new technologies for mining, geophysical surveys, radiation detection, as well as many other studies and measurements. Unfortunately, any operation in underground excavations is associated with exposure to many hazards not necessarily encountered in surface laboratories. One of the most dangerous events observed in underground conditions is the dynamic manifestation of rock mass pressure in form of rockburst, roof falls and mining tremors. Therefore, proper evaluation of geomechanical risk is a key element ensuring the safety of work in underground conditions. Finite Element Method-based numerical analysis is one of the tools which allow conducting a detailed geomechanical hazard assessment already at the object design stage. The results of such calculations may be the basis for the implementation of preventive measures before running up the underground facility.

Within this paper, the three-dimensional FEM-based numerical analysis of large-scale underground laboratory located in deep Polish copper mine was presented. The calculations were made with GTS NX software, which allowed determining the changes in the safety factor in surrounding of the analyzed area. Finally, the possibility of underground laboratory establishment, with respect to predicted stress and strain conditions, were determined.
Expanding the spatial coverage of a ground-based station to validate satellite total ozone data; The case of TROPOMI and Athens Dobson
Authors: Varotsos Costas , Xue Yong , Christodoulakis John , Kouremadas George , Fotaki Eleni-Fotini , Lampros Nikos
Published: March 2021

In this work we present the validation results of the daily observations of the Total Ozone Column (TOC) obtained by the TROpospheric Monitoring Instrument (TROPOMI), and the Dobson spectrophotometer No. 118 located in Athens, Greece, (WOUDC Station ID: 293) during the period November 2017 to February 2021. Simultaneous observations of both instruments are used for this validation.

The increased spatial resolution of TROPOMI observations in relation to the push-broom configuration (non-scanning) of the instrument (swath width of ~2600 km) offers the opportunity to study the spatial analysis of the observed differences in a large area around the ground-based station. By using the ground-based station in Athens we attempt to analyze spatial and temporal behavior of the TOC differences between Dobson and TROPOMI data in an area enclosed by a 500 km radius during the period from August 2019 to February 2021.
Modelling windfarm wakes in operational forecasting model HARMONIE-AROME
Authors: Theeuwes Natalie , van Stratum Bart , van Ulft Bert , Barkmeijer Jan , Basu Sukanta , Wijnant Ine
Published: March 2021

Wind power production in the European Union (EU) is steadily increasing, specifically on the North-Sea. Wind farms are growing both in number and size, while weather models evolve to higher resolutions. This means that the effect of wind farms can no longer be ignored by weather prediction models. Wind farms essentially decelerate the wind (blockage and wake effects) and increase turbulence, indirectly influencing temperature and humidity. In this study, we have included the widely used Fitch et al. (2012) windfarm parameterisation in the operational mesoscale model HARMONIE-AROME. Using our method, we are able to include individual turbines both on- and offshore. The model is evaluated using various datasets, e.g. production data from Elia (Belgium), floating lidar measurements at Borssele Wind Farm, and anemometer measurements from the FINO-towers. The inclusion of the windfarm parameterisation improves the wind forecast near wind farms, also improving the estimate in power production. In addition, we are able to model the effects of wind farms on the boundary-layer temperature and humidity.

Fitch, A. C., Olson, J. B., Lundquist, J. K., Dudhia, J., Gupta, A. K., Michalakes, J., & Barstad, I. (2012). Local and mesoscale impacts of wind farms as parameterized in a mesoscale NWP model. Monthly Weather Review, 140(9), 3017–3038.
The ‘global tree restoration potential’: a first estimation of the hydrological effects
Authors: Hoek van Dijke Anne J. , Benedict Imme , Mallick Kaniska , Herold Martin , Machwitz Miriam , Schlerf Martin , Teuling Adriaan J.
Published: March 2021

Vegetation plays an important role in the exchange of water between the land surface and the atmosphere through evaporation and redistribution of water. Hence, changes in vegetation cover alter the terrestrial hydrological cycle. Large-scale forest restoration is an effective climate change mitigation strategy through carbon sequestration and is expected to impact the water availability. A better understanding of the impact of reforestation is needed, given the numerous different reforestation missions.

Our study aims to provide an estimation of the hydrological effects of 900 million hectares of reforestation, called the ‘global tree restoration potential’ (Bastin et al., 2019). We include the effects of forest planting on evaporation and moisture recycling, where evaporation effects local water availability, and moisture recycling effects both local and remote water availability. We used the conventional Budyko’s moisture index framework to calculate the effects of reforestation on evaporation, and afterwards we used the UTrack dataset to calculate the changes in precipitation. The UTrack dataset presents the monthly climatological mean atmospheric moisture flows from evaporation to precipitation and is created using the Lagrangian moisture tracking model UTrack (Tuinenburg et al., 2020).

The results show that reforesting the ‘global tree restoration potential’ would effect water availability for most of the Earth’s surface. The global mean increase in terrestrial evaporation is 8 mm yr-1. The increase in evaporation is highest around the equator (on average 20 mm yr-1), with local maximum changes of up to 200 mm yr-1. This is related to a relatively high restoration potential in low latitude areas, and a generally large evaporation response in high precipitation regions. Enhanced moisture recycling has the potential to partly compensate for this decreased water availability by increasing the downwind precipitation.

 

Bastin, J.-F., Finegold, Y., Garcia, C., Mollicone, D., Rezende, M., Routh, D., Zohner, C.M., Crowther, T.W. The global tree restoration potential. Science, 365, 76-79, http://doi.org/10.1126/science.aax0848, 2019.

Tuinenburg, O. A., Theeuwen, J. J. E., and Staal, A.: High-resolution global atmospheric moisture connections from evaporation to precipitation, Earth Syst. Sci. Data, 12, 3177–3188, https://doi.org/10.5194/essd-12-3177-2020, 2020.
New scientific diagnostics in the ESMValTool – an overview
Authors: Bock Lisa , Hassler Birgit , Lauer Axel ,   ESMValTool Develpoment Team
Published: March 2021

The Earth System Model Evaluation Tool (ESMValTool) has been developed with the aim of taking model evaluation to the next level by facilitating analysis of many different ESM components, providing well-documented source code and scientific background of implemented diagnostics and metrics and allowing for traceability and reproducibility of results (provenance). This has been made possible by a lively and growing development community continuously improving the tool supported by multiple national and European projects. The latest major release (v2.0) of the ESMValTool has been officially introduced in August 2020 as a large community effort, and since then several additional smaller releases have followed.

The diagnostic part of the ESMValTool includes a large collection of standard “recipes” for reproducing peer-reviewed analyses of many variables across ESM compartments including atmosphere, ocean, and land domains, with diagnostics and performance metrics focusing on the mean-state, trends, variability and important processes, phenomena, as well as emergent constraints. While most of the diagnostics use observational data sets (in particular satellite and ground-based observations) or reanalysis products for model evaluation some are also based on model-to-model comparisons. This presentation gives an overview on the latest scientific diagnostics and metrics added during the last year including examples of applications of these diagnostics to CMIP6 model data.
Do Intraplate and Plate Boundary Fault Systems Evolve in a Similar Way with Repeated Slip Events?
Authors: Shipton Zoe , McKay Lucy , Lunn Rebecca , Pytharouli Stella , Roberts Jennifer
Published: March 2021

As repeated slip events occur on a fault, energy is partly dissipated through rock fracturing and frictional processes in the fault zone and partly radiated to the surface as seismic energy. Numerous field studies have shown that the core of intraplate faults becomes wider on average with increasing total displacement (and hence slip events). In this study we compile data on the fault core thickness, total displacement and internal structure (e.g., fault core composition, host rock juxtaposition, slip direction, fault type, and/or the number of fault core strands) of plate boundary faults to compare to intraplate faults (within the interior of tectonic plates). Fault core thickness data show that plate boundary faults are anomalously narrow by comparison to intraplate faults of the same displacement and that they remain narrow regardless of how much total displacement they have experienced or the local structure of the fault. By examining the scaling relations between seismic moment, average displacement and surface rupture length for plate boundary and intraplate fault ruptures, we find that for a given value of displacement in an individual earthquake, plate boundary fault earthquakes typically have a greater seismic moment (and hence earthquake magnitude) than intraplate events. We infer that narrow plate boundary faults do not process intact rock as much during seismic events as intraplate faults. Thus, plate boundary faults dissipate less energy than intraplate faults during earthquakes meaning that for a given value of average displacement, more energy is radiated to the surface manifested as higher magnitude earthquakes. By contrast, intraplate faults dissipate more energy and get wider as fault slip increases, generating complex zones of damage in the surrounding rock and propagating through linkage with neighboring structures. The more complex the fault geometry, the more energy has to be consumed at depth during an earthquake and the less energy reaches the surface.
Large-scale fluid circulation in deep subduction interfaces: implications on fast and slow earthquake-related processes
Authors: Muñoz-Montecinos Jesús , Angiboust Samuel , Garcia-Casco Antonio , Glodny Johannes , Bebout Gray
Published: March 2021

Devolatilization and fluid-rock interaction processes along subduction interfaces, in particular at depths where episodic tremor and slip events (ETS) are inferred, are evidenced by the occurrence of metamorphic veins in exhumed metamorphic terranes. We investigate the late Cretaceous lawsonite blueschist-facies Seghin complex, part of the Zagros suture zone (Iran), a well-preserved paleo-subduction mélange composed of an antigorite-rich matrix wrapping foliated metatuffs and minor carbonate-bearing metasediments. We first focus on characterizing the relative chronology, conditions of deformation and potential fluid source(s) of Lws+Cpx+Gln veins and aragonite-filled explosive hydraulic breccias. Petrological, geochemical as well as O-C and Sr-Nd isotopic systematics of silicate-rich veins suggest formation mostly from internal devolatilization. This stage is followed at near peak burial conditions by pervasive, externally-derived fluid influx events, with fluids characterized by REE enrichments, and geochemical signatures indicating mixing between metasedimentary-derived fluids and far-traveled mafic-ultramafic-derived fluids. Our geochemical and petrological observations suggest that a host rock-buffered isotopic homogenization occurred between the infiltrating fluids and the rock matrix.

The high pore fluid pressures that enabled the formation of these deep veins also enabled the formation of shallower fault-related rocks including breccias, foliated cataclasites and fluidized ultracataclasites, intimately associated with extensional Gln-bearing veins and Lws+Gln+Ph+Ab fluid-filled pockets. Mineral assemblages reveal that this faulting occurred upon exhumation throughout the lawsonite blueschist-facies (i.e. 35 to 20 km depth). Crosscutting relationships among multiple generations of fluidized ultracataclasites and extensional veins show that episodic seismic faulting and hydrofracturing were contemporaneous processes. Mechanical modelling confirms that the studied fault-related features can only form under nearly lithostatic pore fluid pressure conditions, maintaining the system in a critically unstable regime that promotes recurrent seismic faulting. We propose a large-scale tectonic model in which deeply produced H2O-rich fluids are transported as highly pressurized “pulses” over tens of km parallel to the subduction interface, triggering episodic hydrofracturing and host rock-buffered isotopic homogenization within the ETS region. The mechanical consequence of these events is the triggering of unstable slip within the seismogenic window, as deduced in this unique record of blueschist-facies crustal paleo-earthquakes. These results shed a new light on the physical nature of the numerous moderate magnitude events (Mw=3-6) that are extensively recorded nowadays in Mariana-type plate boundary systems.
Ice nucleating particle concentrations in Dust Regional Atmospheric Model (DREAM) – going one step further
Authors: Ilić Luka , Marinou Eleni , Jovanović Aleksandar , Kuzmanoski Maja , Ničković Slobodan
Published: March 2021

Mineral dust particles in the atmosphere have a large influence on the physical properties of clouds and their lifecycle. Findings from field experiments, modeling, and laboratory studies suggest that mineral dust particles are very efficient ice-nucleating particles (INPs) even in regions distant from the desert sources. The major sources of mineral dust present in the Mediterranean basin are located in the Sahara Desert. Understanding the significance of mineral dust in ice initiation led to the development of INPC parameterizations in presence of dust for immersion freezing and deposition nucleation processes. These parameterizations were mineralogically indifferent, estimating the dust ice nucleating particle concentrations (INPCs) based on dust concentration and thermodynamic parameters. In recent studies, feldspar and quartz minerals have shown to be significantly more efficient INPs than other minerals found in dust. These findings led to the development of mineralogy-sensitive immersion freezing parameterizations. In this study, we implement mineralogy-sensitive and mineralogically-indifferent INPC parameterizations into a regional coupled atmosphere-dust numerical model. We use the Dust Regional Atmospheric Model (DREAM) to perform one month of simulations of the atmospheric cycle of dust and its feldspar and quartz fractions during Saharan dust intrusion events in the Mediterranean. EARLINET (European Aerosol Lidar Network) and AERONET (AErosol RObotic NETwork) measurements are used with POLIPHON algorithm (Polarization Lidar Photometer Networking) to derive cloud-relevant dust concentration profiles. We compare DREAM results with lidar-based vertical profiles of dust mass concentration, surface area concentration, number concentration, and INPCs. This analysis is a step towards the systematic analysis of dust concentration and INPC parameterizations performance when compared to lidar derived vertical profiles.
How well do ERA5/WRF generated wind fields reflect the seasonal variability of the spatio-temporal characteristics of wind field, tested for North-Atlantic conditions
Authors: Beyer Hans Georg , Poulsen Tourid
Published: March 2021

Spatial and temporal characteristics of simulated wind ﬁelds - stemming from the high-resolution weather model WRF with boundary conditions from ERA5 reanalysis data had been validated against the respective data stemming from measurements regarding annual characteristics as reported by [1]. As one result, the tendency of the WRF sets showed some overestimation of the coherency and underestimation of the power spectral density (PSD).

Here, this investigation is deepened to look on the capability of the modelled data to reflect the variability of the PSD and coherencies of the wind speed fluctuations on a monthly and seasonal (three- monthly) scale.

The intra annual variation of the PSD and the coherence functions are well captured by the WRF-generated wind speeds.  No seasonal dependency can be detected for the underestimation of the spectra from the modelled data. The shape can well be modelled by the approach of [Larsén et al., 2013].  Concerning the coherences, the tendency of an overestimation as detected in the analysis of annual sets, shows up in the seasonal scale in similar magnitude, reflecting a systematic shortcoming of the simulated sets to reflect the spatial inhomogeneity of the field.

[1] Poulsen, T, Beyer, H.G., Cross spectral characteristics of  modelled and measured sets of spatially distributed wind in the Faroe Islands, poster presentation  EGU 2020 (2020)

[2] Larsén, X., Vincent, C., and Larsen, S. (2013). Spectral structure of mesoscale wind over the water. Quarterly Journal of the Royal Meteorological Society, 139:685–700. (2013)
Climatological distribution of dissolved inorganic nutrients in the Western Mediterranean Sea (1981-2017)
Authors: Belgacem Malek , Chiggiato Jacopo , Schroeder Katrin , Barth Alexander , Troupin Charles , Pavoni Bruno
Published: March 2021

Ocean life relies on the loads of dissolved inorganic nutrients (nitrate, phosphate and silicate) and other micro-nutrients into the euphotic layer. They fuel phytoplankton growth that maintains the equilibrium of the food web. Ocean circulation and physical processes continually drive the large -scale distribution of chemicals toward a homogeneous distribution (Williams and Follows, 2003). The biological and biochemical processes counteract this tendency. Therefore, describing nutrient dynamics is important to understand the overall ecosystem functioning.

At global scale, most of the biogeochemical descriptions are based on model simulations and satellite data, since nutrient in situ observations are generally infrequent and not homogeneously distributed in space and time. Climatological mapping is often used to understand the biogeochemical state of the ocean representing monthly, seasonally or annual averaged fields.

Within this context, the western Mediterranean Sea climatology (BGC-WMED) presented here is a product derived from in situ observations, derived from various data sources: in total, 2253 in-situ inorganic nutrient profiles over the period 1981-2017 have been used (Medar/MEDATLAS, Fichaut et al., 2003; the CNR-WMED biogeochemical dataset, Belgacem et al., 2020; SeaDataNet data product, https://www.seadatanet.org; Mediterranean Ocean Observing System for the Environment, MOOSE, http://www.moose-network.fr/).

Annual mean gridded nutrient fields for the period 1981-2017, and sub-periods 1981-2004 and 2005-2017, on a horizontal 1/4° × 1/4° grid have been produced. The biogeochemical climatology is built on 19 depth levels and for the dissolved inorganic nutrients nitrate, phosphate and orthosilicate. To generate smooth and homogeneous interpolated fields, an advanced N-dimensional version of DIVA, DIVAnd v2.5.1 (Barth et al., 2014), which is based on the variational inverse method (VIM) (Brasseur et al., 1996), has been used.

A sensitivity analysis was carried out to assess the comparability of the data product with the observational data. The BGC-WMED has then been compared to other available data products, i.e. the medBFM biogeochemical reanalysis and the biogeochemical component of WOA18.

Keywords: Mediterranean Sea, climatology, inorganic nutrient, in situ observations. 
Proof of the zeroth law of turbulence in one-dimensional compressible magnetohydrodynamics and heating of the sawtooth solar wind
Authors: David Vincent , Galtier Sébastien
Published: March 2021

The zeroth law of turbulence is one of the oldest conjecture in turbulence that is still unproven. We consider weak solutions of one-dimensional (1D) compressible magnetohydrodynamics (MHD) and demonstrate that the lack of smoothness of the fields introduces a new dissipative term, named inertial dissipation, into the expression of energy conservation that is neither viscous nor resistive in nature. We propose exact solutions assuming that the kinematic viscosity and the magnetic diffusivity are equal, and we demonstrate that the associated inertial dissipation is, on average, positive and equal to the mean viscous dissipation rate in the limit of small viscosity, proving the conjecture of the zeroth law of turbulence.

We show that discontinuities commonly de- tected by Voyager 1 & 2 in the solar wind at 2–10AU can be fitted by the inviscid analytical profiles. We deduce a heating rate of ∼ 10−18 Jm−3s−1 , which is significantly higher than the value obtained from the turbulent fluctuations. This suggests that collisionless shocks are a dominant source of heating in the outer solar wind.