bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon allocation to wood formation in an unmanaged deciduous forest in Thuringia (Germany)-a case study of biomass production efficiency
Authors: Wei Jingshu , Karamihalaki Maria , von Arx Georg , Babst Flurin
Published: March 2020

Carbon allocation to wood formation is the key process that drives biomass accumulation in forest ecosystems. Particularly important from a carbon balance perspective is the fraction of carbon taken up through photosynthesis (i.e. gross primary productivity) that is allocated to and sequestered in long-lasting wood tissues. This fraction is known as “biomass production efficiency” and a comprehensive understanding of its inter- and intra-annual variability in response to climatic fluctuations and ecosystem dynamics is still lacking. In this study, we assessed and reconstructed the above-ground biomass increment of three deciduous tree species, European beech (Fagus sylvatica), Sessile oak (Quercus petraea) and European hornbeam (Carpinus betulus) in Hainich National Park, Thuringia (Germany). Trees were sampled in a fixed plot design within the footprint area of a long-term eddy-covariance site (DE-Hai). We applied allometric equations to estimate tree volume and combined them with tree-ring width and wood density measurement to quantify and reconstruct the carbon stored as above-ground biomass in wood tissues. We scaled these measurements from the tree to the plot level and integrated the annual biomass increment with the carbon fluxes from the tower to quantify biomass production efficiency. Finally, we correlated species-specific growth with carbon fluxes and various climate parameters at daily, monthly, seasonal, and annual resolution to better understand, how climate variations affect carbon allocation to wood growth at this site. Our study represents a well-constrained observational framework to provide both quantitative and qualitative information on forest carbon cycling that can be used, e.g., to better parameterize tree-centered mechanistic vegetation models.
South Asian summer monsoon in warm epochs of Mid-Holocene and end of 21st century; new insights from high resolution simulations
Authors: Mudra B Lekshmi , Sabin Thazhe Purayil , Krishnan Raghavan
Published: March 2020

The mid-Holocene (MH) was a warmer period, similar to the end of the 21st century climate under high emission realizations. The Indus valley civilization believed to be flourished under the expense of enhanced south Asian summer monsoon precipitation associated with the northward migration of the Inter Tropical Convergence Zone (ITCZ) during the mid-Holocene (MH). However, such an enhanced precipitation is not visible over the northwest India and Pakistan belt in future projection. The role of dynamical and various teleconnection factors behind the enhanced MH precipitation over the Indus valley region is still elusive due to the limitation of course resolution modelling efforts available so far as part of the various phases of Paleoclimate Modelling Intercomparison Projects (PMIP).  To overcome this limitation, we have designed high resolution Paleo-climate simulations using a state-of-the-art variable resolution global climate model (LMDZ: Laboratoire Meteorologie Dynamique and Z stand for zoom) which configured with a 35 km spatial resolution over the South Asian region. We conducted various sensitivity experiments to understand the role of dynamics and teleconnection in enhancing monsoon precipitation over the Indus valley in addition to the MH orbital conditions. Boundary conditions from the PMIP-3, CMIP5 and HadISST datasets utilized for various sensitive experiments. High resolution, clearly demonstrates value addition in simulating the enhanced MH precipitation over Northwest India and adjoining Indus basin associated with the northward migration of the ITCZ and shift in the ascending branch of Hadley cell. We explored the role of various oceanic and atmospheric factors responsible for this enhanced Indus valley precipitation through linearized moisture budget analysis and comparing the relative strength and position of Hadley cell. By further decomposing the thermodynamic and dynamic term into their advection and divergence component, we could demonstrate the role of moisture convergence due to the strengthened atmospheric circulation through the oceanic teleconnection, which additionally  plays a crucial role in enhanced MH precipitation comparing to the dynamical factors. Idealized simulation with the end of 21st century warm condition with the MH orbital forcing and various teleconnection patterns affirms that the thermodynamically induced future precipitation and circulation changes, may not be adequate to make a profound shift in the northern limit of the ITCZ towards its MH locale rather producing enhanced precipitation over the north Indian ocean and localized extreme precipitation over Indian landmass.

Keywords: Indus Valley civilization, Mid-Holocene, Monsoons, Teleconnection, ITCZ and Hadley circulation
Visualization Techniques at the Aviation Weather Testbed
Authors: Cross Austin
Published: March 2020

The  Aviation Weather Center (AWC) is part of the US National Weather Service, providing domestic and global aviation weather forecasts and warnings. Forecasters and automated systems disseminate up to date information including through our website, aviationweather.gov. Recent years have seen AWC transition from primarily text-based products to increasing interactive and graphical tools. While nearly all information is presented in two dimensions, recent work has focused on adding three- and four- dimensional visualizations to increase understanding in the user community. Web based technologies allow interrogating large datasets on-the-fly without specific software installed on the client device, while providing a more complete picture and development of conceptual models beyond fixed horizontal slices of airspace.
Volcanic Jet Noise from the Kilauea Fissure 8 Lava Fountain
Authors: Gestrich Julia , Fee David , Lyons John , Patrick Matthew , Parcheta Carolyn , Kueppers Ulrich , Cigala Valeria
Published: March 2020

Seismic and acoustic signals are important for remote real time and post-eruption analysis of volcanic eruptions. To properly interpret these signals it is critical to connect their characteristics with eruption parameters. In this study, we present an analysis of the infrasound emissions by the sustained lava fountain at Fissure 8 during the 2018 eruption of Kilauea Volcano, Hawaii. This eruption was one of the largest and most destructive events in Hawaii’s historic times. Large (35.5 km2) lava flows covered much of the Lower East Rift Zone (LERZ) and destroyed property and infrastructure. This activity was dominated by high lava effusion rates at Fissure 8 and lava fountains up to 80 m tall. The energetic output of gas and lava produced sustained, broadband acoustic waves which were recorded by a four-element infrasound array deployed 0.6 km northwest of the fountain. The spectrum of the infrasound is similar to that of man-made jets and is termed volcanic jet noise. We compare the spectrum of the recorded infrasound signal with models developed for man-made jets such as rockets and jet engines. These models predict different spectral shapes for fine scale turbulence (FST), produced by incoherent movement of the gases, and large scale turbulence (LST), produced by coherent instability waves. The dominance of one or the other turbulent noise source is highly directional. We compare the infrasonic signals with observations of fountain properties, such as pyroclast velocity and height, to help understand the jet noise signals and determine quantitative fountain properties from the infrasound. The results of this work will contribute to the understanding of the physics of lava fountain sound generation, its dependence on eruption parameters, and ultimately provide a tool for rapid assessment of eruption style and dynamics.
Synoptic climatology and changes in precipitation associated with the South Atlantic Convergence Zone utilising a cloud band identification technique
Authors: Zilli Marcia , Hart Neil
Published: March 2020

Austral wet season precipitation (October through March) in the subtropical parts of Brazil is related to the strength and position of the South American Convergence Zone (SACZ), one of the main features of the South American Monsoon System. The SACZ can be defined as the aggregation of individual tropical-extratropical (TE) cloud bands. Such TE cloud bands have deep convection and heavy rainfall linking the tropical convection over the Amazon rain forest to the mid-latitude weather systems in the Southern Ocean. Utilising a cloud band identification technique, which consists of an object-based algorithm that identifies TE interactions, we detected individual weather systems and explored their associated precipitation characteristics and changes since 1980. Each event is characterised by the total precipitation within the contour of the low-value OLR. For this, we considered three different datasets: observed precipitation from various weather stations over Brazil, gridded to a 0.25° lat/lon resolution; satellite-based rainfall from TRMM (version 3B42); and reanalysis-based precipitation from ERA5. Here we explore the spatial characteristics and associated precipitation statistics of the SACZ events identified through the proposed technique. The monthly spatial signature of the selected events is similar among the three data sources and corresponds to the SACZ location. The selected events account for 25% to 50% of the total monthly precipitation during the wet season, with the largest percentages occurring in December and January. Over South-eastern Brazil, we identified a reduction in the number of events and in total precipitation during these events, resulting in a reduction of their contribution to the total precipitation climatology during the last decade. The drying trends occur mostly in December; in January, the areas with reduced precipitation migrate northward and precipitation increases over Southern Brazil, suggesting that the poleward migration of the SACZ is more pronounced during these months. These results demonstrate the relationship between synoptic systems and the changes in the location of the SACZ described in recent studies. In the next steps, we will diagnose the reanalysed and climate-simulated circulations associated with these events, identifying possible mechanisms responsible for the poleward shift of the SACZ.
Geochemical characterization of discrete grain size fractions within contemporary alpine dust, Uinta Mountains, Utah, USA
Authors: Olson Pratt , Munroe Jeffrey
Published: March 2020

The contemporary aeolian system is poorly understood due in part to a scarcity of direct measurements of modern dust deposition. The Uinta Mountains of Northeastern Utah, USA are well-suited to the study of contemporary dust owing to their gently sloping, soil-mantled alpine zones and relatively inert, quartzite-dominated bedrock. Capitalizing on this unique setting, eight marble dust traps, as well as one active dust collector, have been installed throughout the mountain range. Previous study of samples from these collectors has supported the quantification of mineral dust inputs to alpine pedogenesis and identified isotopic fingerprints that link dust to potential source regions. This project focuses on dust emptied from these samplers in Fall 2019, representing two years of continuous dust accumulation. The mean dust flux for these years is 4.1 g/m2/y, which corresponds to historic flux measurements ranging from 2.7 g/m2/y to 4.4 g/m2/y. The relatively large dust mass of these multi-year samples allows for samples from each collector to be split into a coarse and fine fraction prior to further analysis. Before separation, the median grain size of 2019 dust samples is approximately 10 µm. After sample separation, carried out through timed settling following Stoke’s Law, the approximate median particle diameter is 6 µm for the fine fraction, and 20 µm for the coarse fraction. Coarse Uinta dust is more enriched in quartz and feldspar relative to fine dust, which is dominated by clay minerals. The coarse material is therefore more mineralogically similar to local bedrock, supporting the theory that larger particles are endogenous in origin. Clay minerals are less abundant in local bedrock, suggesting that fine mineral dust may have an exogenous source. Analysis of trace and major elemental abundances, as well as Sr and Nd isotopic fingerprinting will support additional interpretations about the nature and origin of modern dust in the Uintas. These results will contribute to ongoing efforts to better understand how specific dust source regions influence the properties of mineral aerosols arriving in remote alpine environments.
Morphological and ice dynamic changes induced by the formation of proglacial lakes in Exploradores Glacier, Patagonia.
Authors: Irarrazaval Bustos Inigo , Dussaillant Alejandro , Iribarren Anacona Pablo , Vivero Sebastián , O'Kuinghtton Jorge , Mariethoz Gregoire
Published: March 2020

Glacier dynamics are sensitive to the formation and expansion of proglacial lakes. Proglacial lakes development can accelerate glacier retreat rate by flotation of the terminus, formation of a calving front, and increased ice flow. Understanding the impacts of proglacial lakes formation and development, which are reported to be growing in number in Patagonia and other regions, is relevant to improve the understanding and prediction of glacier response to climate change.

This study aims to characterize and monitor recent spatial and temporal changes in the lower section of the Exploradores Glacier (15 km2), located at the northeast section of the Northern Patagonian Icefield. A proglacial lake located at the east margin has been expanding by calving since the early 2000s, and supraglacial ponds located at the front of the glacier could coalesce to form a larger proglacial lake.

We performed repeated unmanned aerial vehicle (UAV) surveys to obtain a series of high-resolution orthoimages (10cm/pixel) and digital elevation models (DEM) of the lower section of Exploradores Glacier. The series consists in 7 orthoimages and DEMs across one year (March 2019 to March 2020), forming in a dataset that is the first of its kind for a Patagonian glacier. The images are processed by photogrammetric technique structure from motion using Pix4D software, and are co-registered using stable off glacier tie-points. Next, the orthoimages are correlated using a feature tracking algorithm (IMCORR) to derive glacier flow velocities. Surface lowering and morphological changes is obtained by DEM differencing analysis. In addition, an aerial photographic archive (Aniya et al. 2017) providing a 20-year observation record is incorporated in the analysis. The results of the imagery analysis are compared with in-situ ablation stakes measurement during the summer season 2019-2020, which indicates downwasting rates up to 100mm/day. This allows estimating rates of proglacial lake expansion at the east margin, supraglacial lakes coalescence, and increase in debris-covered area.

This study contributes to a better understanding of the processes that occur during a relatively short period in a highly transient glacier. Future work will include modelling ice dynamics to better characterize and predict the response of the glacier to the development of proglacial lakes.
Improving tsunami forecast with data assimilation on dense pressure gauge arrays: the 2009 Dusky Sound, New Zealand, tsunami
Authors: Gusman Aditya , Sheehan Anne , Satake Kenji
Published: March 2020

Tsunami warnings in New Zealand rely on first locating and determining size of a large earthquake and then using precomputed simulation results to forecast the threat level and timing of the resulting tsunami. The number of offshore pressure gauges for tsunami monitoring around the world is increasing and it provides the opportunity to develope new methods to forecast tsunamis. In cases where a dense array of offshore pressure gauges is available, a data assimilation method can be applied to estimate the tsunami using the observations of pressure changes. Here we apply the data assimilation method to the tsunami generated from the 2009 Dusky Sound, New Zealand, magnitude 7.8 earthquake and determine a rapid and accurate estimate of the tsunami wave arrival time and size along the west coast of New Zealand.  The tsunami was recorded by the Marine Observations of Anisotropy near Aotearoa (MOANA) OBS network which consists of a total of 30 differential pressure gauges.

We use tsunami waveform inversion applied to Deep‐ocean Assessment and Reporting of Tsunamis (DART) offshore pressure gauge and coastal tide gauge data to estimate the fault slip distribution of the Dusky Sound earthquake. The tsunami from this fault slip estimate is then used as a reference to measure the forecast accuracy from different methods to forecast the tsunami threat in New Zealand’s tsunami warning zones. Methods that are evaluated here include the currently operational tsunami warning procedure in New Zealand, tsunami data assimilation that relies only on the dense pressure gauge array data, and tsunami data assimilation with an initial condition model from W-Phase inversion result.

A good match was found between the forecast from the data assimilation method and observed tsunami waveforms at the Charleston tide gauge station on the west coast of New Zealand's South Island. However, this method gives an accurate forecast only along the west coast of New Zealand because the offshore pressure gauge network is located off the west coast of the South Island. While an advantage of the data assimilation is that no initial condition is needed, we find that our forecast is improved especially along the south and east coasts of the South Island by merging tsunami forward modelling from a rapid W‐phase earthquake source solution with the data assimilation method.
Magnetoclinicity: Density variance effects in large-scale instability in magnetohydrodynamic turbulence
Authors: Yokoi Nobumitsu
Published: March 2020

In the presence of strong compressibility an oblique configuration between the mean density gradient and magnetic field contributes to the electromotive force [1,2]. This effect can be called “magnetoclinicity” and may contribute to the formation of large-scale magnetic-field structure in compressible magnetohydrodynamic (MHD) turbulence. With the aid of the multiple-scale direct-interaction approximation (Multi-Scale DIA), a combination of the DIA and multiple-scale analysis, analytical expressions of the turbulent correlations (turbulent electromotive force, turbulent mass flux, turbulent heat flux, Reynolds stress, turbulent Maxwell  stress, etc.) are obtained for the compressible MHD turbulence. Utilizing these analytical results, a large-scale instability of the strongly compressible MHD turbulence is investigated. An analysis into normal modes of the periodic plane waves is performed to get a dispersion relation of the instability modes [3]. It is shown that, depending on the mean density configuration, the inhomogeneity of the mean density variation coupled with the density variance <ρ'2> (ρ': density fluctuation, <...>: average) leads to a finite growth of the mean magnetic disturbance at large scales. This magnetoclinicity effect counter-balance to the turbulent magnetic diffusivity, and contribute to the formation of large-scale magnetic fields. This magnetoclinicity effect is expected to play essential roles in global structure formation in strongly compressible plasma turbulence.

Reference

[1] N. Yokoi, “Electromotive force in strongly compressible magnetohydrodynamic turbulence,” J. Plasma Physics, 84, 735840501, pp.1-26 (2018).

[2] N. Yokoi, “Mass and internal-energy transports in strongly compressible magnetohydrodynamic turbulence,” J. Plasma Physics, 84, 775840603, pp.1-30 (2018).

[3] S. Chandrasekhar, Hydrodynamic and Hydromagnetic Stability (Oxford University Press, 1961).
BepiColombo – Status and first Results from Activities during Cruise and the Earth flyby
Authors: Benkhoff Johannes , Zender Joe , Murakami Go
Published: March 2020

Mercury is a mysterious planet in many ways very different from what scientist were expecting. BepiColombo was launched on 20 October 2018 the BepiColombo from the European spaceport in French Guyana and is now on route to Mercury to unveil Mercury’s secrets. BepiColombo with its state of the art and very comprehensive payload will perform measurements to increase our knowledge on the fundamental questions about Mercury’s evolution, composition, interior, magnetosphere, and exosphere. BepiColombo is a joint project between the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) and consists of two orbiters, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (Mio). 

The BepiColombo spacecraft is during its 7-year long journey to the innermost terrestrial planet in a so-called ‘stacked’ configuration: The Mio and the MPO are connected to each other, and stacked on-top of the Mercury Transfer Module (MTM). Only in late 2025, the ‘stack’ configuration is abandoned and the individual elements spacecraft are brought in to their final Mercury orbit: 480x1500km for MPO, and 590x11640km for Mio. The foreseen orbits of the MPO and Mio will allow close encounters of the two spacecraft throughout the mission. The mission has been named in honor of Giuseppe (Bepi) Colombo (1920–1984), who was a brilliant Italian mathematician, who made many significant contributions to planetary research and celestial mechanics.

On its way BepiColombo has several opportunities for scientific observations - during the cruise into the inner solar system and during nine flybys (one at Earth, two at Venus and six at Mercury). However, since the spacecraft is in a stacked configuration during the flybys only some of the   instruments on both spacecraft will perform scientific observations. In early April of 2020 BepiColombo will flyby Earth and later in October the first Venus flyby will follow.

A status of the mission and instruments and first results of measurements taken during the Earth flyby and the first year in cruise will be given.
Can satellites replace mooring arrays? Satellite altimetry transport estimates of the Atlantic overturning meridional circulation along the RAPID 26°N mooring array
Authors: Sanchez-Franks Alejandra , Frajka-Williams Eleanor , Moat Ben
Published: March 2020

The Atlantic meridional overturning circulation (AMOC) is a large-scale oceanic circulation comprising a 2-layer flow: the net northward flow in the upper 1000 m of the Atlantic and net southward flow below. Variations in the AMOC have significant repercussions for the climate system hence there is a need for proxies that can measure changes in the AMOC on larger spatial scales. Here we show a direct calculation of ocean circulation at 26°N from satellites compares well with transport estimates from the RAPID mooring array. In the surface layer (1000 m), transport is estimated from satellite altimetry and has a correlation of r=0.79 (significant at 95% level) with the MOC transport estimates from RAPID. We find that the relationship between sea level anomaly and dynamic height from the western boundary RAPID moorings is robust in the surface layer, with poor agreement occurring largely below 1000 m. Below 1000 m, the return flow of the AMOC is estimated using ocean bottom pressure from satellite gravimetry. This has a correlation of r=0.75 (significant at the 95% level) when compared to the deeper (1000-5000 m) RAPID transports. Combining the results from satellite altimetry and gravimetry, estimates of full-depth 2-layer circulation at 26°N are demonstrated. Finally, empirical orthogonal function analysis reveals that the barotropic and baroclinic streamfunctions are linked to wind stress curl and buoyancy forcing, respectively.
Piton de la Fournaise, elasto-plastic models of stresses and deformation accounting for the topographic load and a magmatic injection
Authors: Gerbault Muriel , Fontaine Fabrice , Peltier Aline , Gailler Lydie , Hassani Riad , Got Jean-Luc , Ferrazzini Valerie
Published: March 2020

Building on previous work aimed at identifying and characterizing the potential mechanical trigger controlling eruptions and destabilization at Piton de la Fournaise, we study the mechanical behavior of the volcanic edifice on a crustal scale. Do the recurrent earthquake pattern correspond to a destabilization structure, precursor of a large-scale flank sliding? Or instead to a reactivated area of magma storage (partially crystallized “sill”)? To answer these questions, we design numerical models which estimate the stress field associated with the volcanic complex. We use the ADELI finite element method in three dimensions, which handles  elasto-visco-plastic rheologies. In these models, we take into account 1) the topographic load, 2) the major density and resistance heterogeneities within the volcano obtained from previous studies, and 3) the overpressure induced by the intrusion of a dike of arbitrary geometry.
The modeled dike injection generates deformation and stress fields such that their isocontours highlight an ellipsoidal cup structure extending from the central cone to a depth close to 0 and reaching the ends of the eastern flank. This zone could be assimilated to the zone of seismicity observed and described previously. Together with several systematic test cases, we will discuss the significance of these results, such as whether it reveals a rheological delimitation zone of the hydrothermalized bedrock, resulting from the combined influence of the topographic load and that of a magmatic injection.
Macrofauna and roots reduce methane production and attenuate nutrient recycling in organic-rich fluvial sediments
Authors: Benelli Sara , Bartoli Marco
Published: March 2020

Organic-rich freshwater sediments display millimetric oxygen and nitrate penetration and are sources of methane to the water column and to the atmosphere via diffusion and ebullition. Radial oxygen loss by submersed aquatic plants and burrow irrigation with O2 and NO3- enriched water by macrofauna can significantly alter the subsurface sediment volume where respiration processes alternative to methanogenesis occur. We tested this hypothesis in perifluvial organic sediments colonized by the submerged phanerogam Vallisneria spiralis and the oligochaete Sparganophilus tamesis. Gas ebullition and diffusive fluxes were measured in microcosms maintained under controlled laboratory conditions over a period of two weeks. Four conditions were reproduced: sediments alone, sediment with oligochaetes, sediment with plants and sediment with plants and oligochaetes. Microcosms with sediments alone released the largest methane volume whereas sediments with plants and macrofauna released the lowest amount. The presence of the oligochaete had comparatively a stronger effect than that of the macrophyte. Simultaneously, the bioturbation activity of the oligochaete enhanced the production of N2 and the consumption of oxygen and nitrate, suggesting increased rates of aerobic respiration and of denitrification. The presence of plants attenuated net N2 losses from the benthic system likely due to the competition between assimilative and dissimilative N-related processes.
Structure function analysis of plasma density fluctuations during total loss of lock of GPS signal events
Authors: Ghadjari Hossein , Knudsen David , Skone Susan
Published: March 2020

Ionospheric irregularities are fluctuations or structures of plasma density that affect the propagation of radio signals. Whenever large-scale irregularities break up into meso and small-scale irregularities, these processes become similar to a turbulence cascade. In order to have a better comparison between this and plasma density irregularities, we study different orders of structure functions of plasma density of total loss of lock events measured with the faceplate measurements of plasma density and the GPS measurements from the Swarm mission. Total loss of lock of GPS signal is a physical proxy for severe degradation of GPS signals. In addition to different orders of structure-function, we study the existence of self-similarity or multifractality of plasma density of total loss of lock events to investigate any possible intermittent fluctuations. 
Simulation of Aurora basin, East Antarctic
Authors: Zhao Liyun , Zhen Yan , Gladstone Rupert , Zwinger Thomas , Moore John
Published: March 2020

The Aurora basin includes several fast-flowing glaciers (e.g. Totten and Dalton) and has large subglacial areas below sea level, which makes its study an essential part of evaluating the stability of East Antarctic against ocean warming. We use the 3D full-Stokes ice flow model Elmer/Ice to investigate the dynamic processes taking place in this basin. The spatial pattern of basal friction is deduced by inverse method from observed surface velocity. Particular focus is in the thermal condition at the bedrock. We further project the evolution of this basin during the 21st century with parameterized sub-ice shelf melting based provided by high resolution ocean models.
Inside blue dots - Grasping dynamic global fields thanks to Virtual Reality
Authors: Toussaint Renaud , Koelemeijer Paula , Zaroli Christophe
Published: March 2020

Globe representation of the Earth has a long history in pedagogy and outreach. To help people realize global processes, these representations allow the conception and the manipulation of global fields and planetary geography. The realization of a physical representation of such global fields is demanding. 3D printing allows representing well scalar data at a fixed time, via for example the deformation of elevation maps. We propose here an alternative allowing to represent easily dynamic fields, and reproducing in a simple principle the effect obtained by the first astronauts visualizing planet Earth as a "pale blue dot". To that effect, we use virtual reality and represent mobile fields on a globe, associated with a physical object permitting spatial manipulation. The open software Unity, common in videogame conception and development, and the library Vuforia, allowing virtual reality, are utilized for the development. The fields represented are associated with the solid earth, and with oceanic and atmospheric dynamics: Seismic velocity fields, global seismicity catalogs, geoid, geothermal gradient, or oceanic and atmospheric currents. The software is can be easily deployed on tablets and phones, complementing printed images.
Determination of particle transport patterns in a high mountain river influenced by the construction of reservoirs, using particle tracking techniques and hydrodynamic modeling, case study: Río La Miel.
Authors: Santos Granados German Ricardo , Palacios Gonzalez Jordi Rafael , Escobar Varga Jorge Alberto , Corzo Perez Gerald Augusto
Published: March 2020

Particle tracking is very important  for the appropriate management of water resources. Morphological heterogeneities of rivers make the prediction of the particle motions difficult due to the complex numerical and physical variations in the mathematical formulation. Data availability in recent years have allowed to extend dimensionality of the problem and even use coupled models for a better understanding of those patterns. Aside from this, the hydrogeomorphic characteristics of Mountain Rivers are poorly studied around the world. In certain cases, like the river la Miel in Colombia, there are strong dynamic associated with external variables like the operation of a reservoir. The environmental conditions of the operation and the transport of particles are important to determine environmental impacts of the operation. In this research, a hydrodynamic modeling exercise coupled with particle tracking was developed to determine transport patterns.  The development of this model was carried out using the Delft 3D software. Information about the hydrophysical recognition in “La Miel” river downstream of “La Miel” hydroelectric complex located in Caldas -Colombia was gathered in a campaign on 21 and 27 of July 2019. The bathymetries were collected using a ECHOMA 54v, and velocities of the river obtained with and ADCP River Ray, for a 10 km length. Data correction have been done so the digital elevation model was made and the topographic conditions for the construction of the two dimensional hydrodynamic modeling system fitted a logical representation.  Permanent flow was assumed, because the variation of the areas and hydraulic conditions that are only influenced by the rules of Hydroelectric operation. Finally, the hydrodynamic model coupling was performed with the “following-up” model of particles to determine transport patterns. The main result of this research is still to follow in a project that aims to describe the movement and behavior of small marine species, the travel trajectory of a pollutant and other local uses such as forensic investigation in rivers. Results will also be used to study the dynamics of high mountain rivers.
Complex basal conditions influence flow at the onset of the North East Greenland Ice Stream
Authors: Franke Steven , Jansen Daniela , Paden John , Eisen Olaf
Published: March 2020

The onset and high upstream ice surface velocities of the North East Greenland Ice Stream (NEGIS) are not yet well reproducible in ice sheet models. A major uncertainty remains the understanding of basal sliding and a parameterization of basal conditions. In this study, we assess the slow-flowing part of the NEGIS in a systematic analysis of the basal conditions and investigate the increased ice flow. We analyze the spectral basal roughness in correlation with basal return power from an airborne radar survey with AWIs ultra-wideband radar system in 2018 and compare our results with current ice flow geometry and ice surface flow. We observe a roughness anisotropy where the ice stream widens, indicating a change from a smooth and soft bed to a harder bedrock as well as the evolution of elongated subglacial landforms. In addition, at the upstream part of the NEGIS we find a clear zoning of the bedrock return power, indicating an increased water content at the base of the ice stream. At the downstream part, we observe an increased bedrock return power throughout the entire width of the ice stream and outside its margins, indicating enhanced melting and the distribution of basal water beyond the shear zones.
Precipitation biases over southern Africa: examining the role of the Angola Low.
Authors: Karypidou Maria Chara , Katragkou Eleni
Published: March 2020

One of the main features controlling precipitation over southern Africa during the wet season is the Angola Low (AL) pressure system that appears as a heat low during October and November and as a tropical low during the climatological mean of December, January and February. The literature provides evidence that wet biases over southern Africa in the Coupled Model Intercomparison Project Phase 5 ensemble (CMIP5) are associated with a strongly simulated AL. In the current work, we examine the degree to which this observation holds for the CORDEX-Africa (Coordinated Regional Climate Downscaling Experiment - Africa) ensemble, using evaluation experiments forced with ERA-Interim at a spatial resolution of 0.44o. The analysis is performed using daily values for months October to March for the period 1990-2008. We characterize the precipitation bias over southern Africa using 10 satellite and gridded precipitation products. For the identification of the AL we use potential temperature at 850 hPa, specific humidity at 850 hPa and relative vorticity at 850 and 500 hPa. Our results highlight the fact that process-based evaluation of climate simulations are key in understanding structural model deficiencies. 
Collaboration for gaming: Partnership between hydrologists, computer scientists, and educators to develop an educational geoscience game
Authors: Gallagher Lisa , Farley Abram , Jourdain Sebastien , O'Leary Patrick , Condon Laura , Maxwell Reed
Published: March 2020

The Integrated Groundwater Modeling Center is a small research center with a focus on hydrological research and a mission to develop and promote education and outreach in our community. We believe that students of all ages learn better when learning is fun, social, and hands-on. We strive to develop games that will immerse and educate users in geoscience concepts by collaborating closely with computer scientists and software engineers. For the work presented here, we have partnered with the University of Arizona and Kitware, Inc., blending technologies and expertise to develop a game to teach hydrogeology concepts.

We have developed an interactive computer simulation of a physical teaching model for students. This computer simulation has a game-like web browser-based interface but builds upon open source software components developed by Kitware (e.g. ParaView and SimPut) executing the integrated hydrology model ParFlow, using a framework built upon the widely used Python scripting language. Students run the simulation using a familiar web-app like interface with sliders and buttons yet are learning real hydrologic concepts and can compare to the physical model. Here, we will present this interactive toolkit and the physical sand tank aquifer model on which it’s based.
Moisture and heat advection as drivers of global ecosystem productivity
Authors: Schumacher Dominik L. , Keune Jessica , Miralles Diego G.
Published: March 2020

Terrestrial ecosystems play a key role in climate by dampening the increasing atmospheric CO2 concentrations primarily caused by anthropogenic fossil fuel emissions. The capability of the land biosphere to act as a carbon sink largely depends on climate conditions, which determine the energy and water availability required by plants to grow. Even though only a small part of the global land area is covered by vegetation, the impact of extreme dry and wet seasons has been shown to largely drive the global interannual variability of gross primary production. The climate in a certain area can be seen as the balance of different heat and moisture fluxes: local surface–atmosphere fluxes from below, entrainment of heat and moisture from aloft, and ‘horizontal’ advection of heat and moisture from upwind regions. The latter provides a mechanism for remote regions to impact gross primary production downwind, and has received less scientific attention. Here, advection is inferred from a bird’s eye perspective, focussing on the five ecoregions with the largest interannual variability in peak productivity around the globe. Employing the atmospheric Lagrangian trajectory model FLEXPART, driven by ERA-Interim reanalysis data, we track the air residing over ecoregions back in time to deduce the origins of heat and moisture that affect ecosystem gross primary production. Utilizing the evaporative source regions supplying water for precipitation to these ecosystems, as well as the analogous source regions of advected heat, we estimate the contribution of advection to gross primary production. Our findings show that source regions of heat and moisture are not congruent: upwind land surfaces typically supply most of the advected heat, whereas upwind oceans tend to provide more moisture. Moreover, low gross primary production in heat-stressed and water-limited ecosystems is often accompanied by enhanced heat and reduced moisture advection from land regions, exacerbated by upwind land–atmosphere feedbacks. These results demonstrate that anomalies in atmospheric advection can cause ecosystem productivity extremes. Particularly in light of ongoing climate change, we emphasize the potentially detrimental effects of upwind areas that may cause long-lasting impacts on the terrestrial carbon budget, thereby further affecting the climate.
A dynamic-statistical approach for probabilistic forecasting of daily soil moisture in the United States
Authors: Medina Hanoi , Tian Di
Published: March 2020

Soil moisture forecasting is important for informing agricultural and environmental management. However, due to the strong interactions between climate, soils and vegetation, even small errors in the weather-related forcing commonly have remarkable impacts on the soil moisture, making soil moisture forecasting especially challenging. Therefore, it is necessary to develop a probabilistic forecasting strategy that accounts for the uncertainty of inputs such as rainfall and evapotranspiration. Here we develop a hybrid dynamic-statistical framework that combines statistical downscaled forecasts of precipitation and reference evapotranspiration from numerical weather predictions (NWP) with a probabilistic water balance model to produce probabilistic forecasts for daily soil moisture at site scale. Forecasts are initialized using in situ measurements over represented locations from the National Soil Moisture Network. We found that the skill of the soil moisture forecasts more relies on the skill of the precipitation forecasts than reference evapotranspiration forecasts. The forecasts are invariably highly skillful over the first 2-3 days, while the skill rapidly decreases over the following days. The soil moisture forecasts based on the statistically post-processed NWP forecasts show higher skill than persistence-based forecasts, climatology forecasts, or forecasts directly retrieved from NWP.
Assessing the atmosphere-surface exchange of gaseous elemental mercury using passive air samplers
Authors: Si Meng , Feigis Michelle , Quant Isabel , Mistry Shreya , Snow Melanie , Breivik Knut , Lafreniere Melissa , Lamoureux Scott , Muir Derek , Steffen Alexandra , Stupple Geoff , Lei Ying Duan , Mitchell Carl , Wania Frank
Published: March 2020

The specific properties of gaseous elemental mercury (GEM) allow it to undergo bidirectional exchange between the atmosphere and the Earth’s surface. Determining the direction and the magnitude of GEM’s atmosphere-surface flux is possible and has been accomplished using micrometeorological and chamber techniques, but (i) is complex and labor-intensive, and (ii) often only yields fluxes over relatively short time scales. A recently developed passive air sampler for GEM has the precision required for identifying and quantifying vertical concentration gradients above the Earth’s surface. The feasibility and performance of this approach is currently being tested in a number of field studies aimed at the: (i) measurement of GEM concentration gradients above both mercury-contaminated and background forest soils, (ii) quantification of vertical concentration gradients on a tower through a temperate deciduous forest canopy, and (iii) measurement of mercury concentration gradients over stable and thawing permafrost to determine the effect of permafrost degradation on GEM evasion. Contrasting with earlier flux studies, these investigations cover long time periods (up to 1.5 years) and have coarse temporal resolution (monthly to seasonally). Significant gradients of GEM air concentrations, both increasing and decreasing with height above ground, were observed, implying that at a minimum, the method is able to identify the flux direction of GEM. Under the right circumstances, this method can also be used to estimate the approximate magnitude of the GEM air-surface exchange flux. The measured gradients also reveal the impact of factors such as temperature, solar irradiance, and snow cover on air-surface exchange. The method holds promise for establishing the direction and size of exchange fluxes at long time scales of months to a year, especially in study areas where access, effort and cost are prohibitive to longer duration studies with existing approaches.
Visualisation and quantification of wheat root system architecture and soil moisture distribution in an aggregated soil using neutron computed tomography
Authors: Mawodza Tinashe , Menon Manoj , Casson Stuart , Burca Genoveva
Published: March 2020

Sustainably intensifying global crop production in a world of diminishing natural resources is paramount for the attainment of zero hunger worldwide (a United Nations sustainable development goal). Key to this sustainable intensification is a deep understanding of the dynamics and complexities of plant-soil interactions for optimisation of plant productivity. Neutron computed radiography and tomography are powerful, non-invasive tools that enable the characterisation of plant-soil systems in situ. They also enable the visualisation and quantification of water distribution and movement within plant-soils systems. In this novel study, we use high resolution neutron computed tomography to investigate root system architectural differences in two different genotypes (Wild type vs TaEPF1-OE1-water use efficient mutant line) of bread wheat (Triticum aestivum). We further investigated how wheat roots interact with the heterogeneously distributed soil moisture. For this investigation, plants were grown in an aggregated sandy loamy soil with moderate amounts of organic matter (4%) for 13 days prior to imaging. We were able to produce a detailed three dimensional visualisation of the root architectural distribution of the two different genotypes imaged. These did not show significant differences between the two genotypes under investigation. We were also able to visualise relative soil moisture distribution and made inferences to how the roots of the wheat plants under investigation interact with the heterogeneously distributed soil moisture. Our results showed increased lateral root growth in regions with finer soil aggregates that had an estimated lower moisture content as compared to larger soil aggregates that retained higher amounts of moisture. This study demonstrates that detailed investigations into plant-soil interactions using neutron imaging techniques can be done successfully even in aggregated soils with considerable amounts of organic matter. This is a departure from the majority of neutron imaging experiments that predominantly use disaggregated sand soils devoid of organic matter as a growth medium.