bluuebunny/crossref_metadata_2025 huggingface dataset:
How Climate Services can provide the knowledge of the expected surfing days on surf-spots in the Iberian Peninsula
Authors: Boqué Ciurana Anna , Aguilar Enric
Published: March 2020

The practice of surf is extended around the Iberian Peninsula’s coast. Surf-spots are the specific nearshore locations where surfing occurs. This coastal sport needs specific environmental conditions to be done. Knowing which is the distribution of surfing days around the Iberian Peninsula is a complex task. This is because good surfing conditions are the result of different climatological, geomorphological and oceanographical variables. Moreover, data collected used to define the distribution of surfing days is registered far away from the shore. Thus, the conditions registered – in the location of the buoys- will change somehow once arrive to the shore where surfers try to perform their best.

Research has explored the advancements of climate services in multiple fields but the determination of frequency of surfing days around the Iberian Peninsula by attributing data from oceanographic buoys to surf-spots was not done before. Atmospheric variability modulates in different temporal scales occurrence and severity of the waves. In this way knowing how the climate works, how the atmosphere exchanges energy with the ocean or how is transferred and how this affects to low pressures and high pressures is fundamental for understanding the conditions for surfing.

In this sense, Climate Services can provide the knowledge of the expected surfing days on surf-spots in the Iberian Peninsula by the methodology created in this study. The aim of this method is to identify the main variables which will make a good day for surfing or not. Into this context is important to know that surfing days are the result of two main factors: the influence of travelling low pressures from the ocean/sea to the specific shore (1) and the local conditions of each specific surf-spot -- thermal winds and beach orientation-- (2). The way of attributing these two factors is using buoys data to know the influence of travelling low pressures from the ocean to the shore by knowing significant wave height in open sea-. Then the form in which are attributed the local conditions is by knowing the specific favourable swell direction needed in each surf-spot and matching the direction of the swell that is registered by the buoys.  In this way, it is made an attribution from the buoy data in the open sea to the surf-spots conditions located on the shore. The main results show the distribution of the expected days for surfing in the Iberian Peninsula based on historical data.

Acknowledgments:

Puertos del Estado from Ministry of Development in Spain and Instituto Hidrográfico marinha Portugal provided the data for doing this study.
Evaluating AquaCrop for simulating response of tomato to irrigation induced salinity
Authors: Ito Yuki , Ben-Gal Alon
Published: March 2020

AquaCrop is considered a reliable simulation model to predict crop yield. AquaCrop is supported by the FAO and seems to provide reasonable balance between accuracy and simplicity. While AquaCrop handles crop response to conditions of salinity, there have been few studies evaluating its accuracy to this parameter. We evaluated AquaCrop for its ability to simulate crop growth, transpiration and yield under conditions of irrigation-induced salinity using an experimental database of tomato grown during different meteorological conditions and demands under highly varied conditions of irrigation water salinity and irrigation amounts.

Field and lysimeter experiments were carried out in the Southern Arava Valley in Israel in fall and spring seasons. Tomato (Lycopersicon esculentum Mill. cultivar ‘5656’) was grown. Irrigation in the field was managed with treatments of 30, 60, 100, and 130% of reference evapotranspiration (ET0) of Class A pan with irrigation water salinity (ECI = electrical conductivity of irrigation water) of 3 dS m-1. Irrigation treatments in the lysimeters were six ECI levels from 1 to 11 dS m-1 all at 130% of ET0 and five irrigation levels of 30, 60, 100, 130 and 160 % of ET0 all at ECI of 3 dS m-1. ECI was regulated adding 1:1 Molar concentrations NaCl and CaCl2. Irrigation was applied via drippers from soil surface covered with polyethylene mulch to reduce evaporative losses to a minimum. AquaCrop was run to calculate yield and transpiration in fall and spring. The datasets of meteorological, crop, management, and soil data were obtained from field-measured results.

Predicted biomass at the end of both growing periods agreed relatively well with measured biomass. Patterns of accumulated transpiration were different in the two seasons, with gradual increase to a stable maximum in the fall and continued increase in the spring. Irrigation level and salinity were found to effect biomass, transpiration and yield alternatively, with irrigation dominant at low ECI levels and salinity dominant when irrigation application was relatively high. Transpiration was simulated well, showing similar trends of the measured data in lysimeters in both fall and spring. The biomass in fall and spring was predicted relatively well. Following these results, AquaCrop appears applicable for simulation of salinity effects on yield and transpiration, at least under conditions similar to those of the current study.
Strain dependent microfabric evolution of experimentally deformed synthetic eclogites
Authors: Thospann Philipp , Incel Sarah , Fusseis Florian , Butler Ian B. , Renner Jörg , Rogowitz Anna
Published: March 2020

Deformed eclogites often reveal interconnected layers of omphacite and intercalated elongated garnet clusters. The evolution of such fabrics is usually associated with strain localization and rheological weakening. To better understand the onset of strain localization in eclogite, we experimentally investigate the strain-dependence of microfabrics in omphacite-garnet aggregates. Eclogites were synthesized by hot-pressing omphacite-garnet powders (with a volume fraction of 25% garnet) in a piston-cylinder press at 3 GPa and 1100 °C for 24 h. These synthetic eclogites were then axially shortened by ~3.5%, ~4.7%, ~17% and ~40% in a Griggs-type deformation apparatus at 2.5 GPa, 900°C, and a strain rate of 6.4·10-6 s-1. The low-strain experiments document microstructures developing near the material’s yield point at ~4% axial strain, whereas the highly strained samples reached nearly mechanical steady state with minor strain weakening. The recovered samples were analyzed using an X-ray microtomography instrument (μCT) which provides quantitative volume, shape and spatial arrangement data in three dimensions. By utilizing optical light microscope, scanning electron microscope and electron backscatter diffraction analyses in combination with the μCT data we identified the dominant deformation mechanisms operating at different strains and linked them to the microfabric. At low strain, omphacite exhibits a weak shape preferred orientation (SPO) and garnet tends to form clusters. The highly strained samples show a strong foliation with elongated omphacite crystals exhibiting a pronounced SPO and garnet clusters being arranged into elongated layers perpendicular to the maximum compressive stress. A reduction in grain size and an increase in density of low-angle grain boundaries with increasing strain indicate deformation of omphacite by dislocation creep. Elongated garnet clusters show brittle deformation in the form of micro-cracking. Evidence for minor crystal-plastic deformation in garnet occurs locally at the proximity of the grain boundaries where high differential stresses tend to localize resulting in increased misorientation. Similar to naturally deformed eclogites, we observe a layering of omphacite and garnet in our experimental samples, in which omphacite generally accommodated most of the strain while garnet grains behaved essentially like rigid bodies.
IrrigaSys – a decision support system for irrigation management in the Sorraia Valley region, Portugal
Authors: Simionesei Lucian , Ramos Tiago B. , Palma Jorge , Oliveira Ana R. , Neves Ramiro
Published: March 2020

IrrigaSys is a decision support system (DSS) for irrigation water management based on online, open
access tools. The system includes remote access to local meteorological stations for weather
conditions, a MM5 model for weather forecast, the MOHID-Land model for the computation of the
soil water balance and irrigation scheduling, and a MySQL database for data repository. Despite its
complexity, the data necessary to run IrrigaSys is minimal, and include the location of the agricultural
field, crop type, sowing and harvest dates, soil texture, irrigation method, and daily/weekly irrigation
depths applied by the farmer. Based on this information, the system automatically downloads the
weather data from the meteorological station located closest to the agricultural plot, as well as the
weather forecast for the seven days following the current date. The soil water balance is then
computed for the previous and following week as well as the crop irrigation needs using the MOHIDLand
model. Results are made available via a web interface, a mobile app, SMS, and email. Besides the
model outputs, the IrrigaSys further provides the Normalized Difference Vegetation Index (NDVI) for
the agricultural field. The NDVI is computed from Sentinel 2 spectral bands with a resolution of 10m,
and is updated every time new Sentinel 2 imagery data (with cloud cover < 10%) is available. The
IrrigaSys has been developed in close cooperation with the Water Board Association of the Sorraia
Valley irrigation district (15360 ha), southern Portugal, over the last 5 years, supporting 103 plots of
30 farmers during the last irrigation season. As a result, the main limitation is naturally associated to
the difficulty in providing reliable estimates for all field plots based on calibrated model data. As the
next step, the service should start automatically identifying the culture status based on satellite
information as well as providing fertigation recommendations to farmers.
Rapid, continuous radiocarbon analysis of carbonate archives using laser ablation
Authors: Wertnik Melina , Welte Caroline , Wacker Lukas , Yeman Christiane , Hattendorf Bodo , Koch Joachim , Christl Marcus , Fohlmeister Jens , Synal Hans-Arno , Eglinton Timothy I.
Published: March 2020

While high-precision radiocarbon (14C) measurements of carbonaceous samples using Accelerator Mass Spectrometry (AMS) have become routine, achieving a continuous radiocarbon record for carbonate archives (e.g. speleothems, corals) still requires labor-intensive and time-consuming sample preparation. By feeding laser ablation (LA) generated CO2/CO online into a gas source AMS, however, these archives can be sampled continuously and with minimal preparation efforts.

The LA-AMS setup installed in 2013 at ETH Zurich [1] has recently been improved in order to achieve higher signal intensities and consequently higher measurement precision as well as simpler instrumental maintenance. By redesigning the sample cell and reducing the optical path length of the laser, the fluence on the sample could be increased from previously 1-2 J cm-1 to now 8-23 J cm-1, leading to more efficient generation of gaseous carbon from CaCO3. The laser spot size was reduced from 110 μm x 680 μm to 75 μm x 140 μm, improving the overall spatial resolution of the setup. The background level of the method has been determined to have a F14C of 0.009 ± 0.002 and reaches a precision of less than 1% for modern samples.

To fully exploit the advantages of this unique technique, a LA-AMS specific data analysis software to disentangle [2] the quasi-continuous data stream is being developed. Features implemented include correlation of data with sampling location and plotting of all relevant measurement parameters as a function of sampling location (F14C,
Chemical-mechanical-hydraulic coupling in deforming, dehydrating halite-gypsum rocks - implications for basal detachments in thin-skinned tectonics
Authors: Marti Sina , Fusseis Florian , Butler Ian B , Schlepütz Christian , Marone Welford Federica , Gilgannon James , Kilian Rüdiger , Yang Yili
Published: March 2020

Long-distance transport along weak basal detachments in thin-skinned tectonics is often accomplished by rheologically weak evaporites. This weakness can be attributed to  the behavior of gypsum and/or halite. While the former dehydrates and the released fluid reduces the effective stress in the system, the latter is known to be extremely weak at the corresponding conditions. Separately, both minerals and their behavior under tectonic loading have been studied in great detail. However, these studies on single minerals are limited in that natural detachments are often not monomineralic and are clearly affected by interdependencies between different mineral species. In evaporitic sequences, two key couplings that can be expected are: 1) the sensitivity of the dehydration reaction to the pore fluid pressure versus the notoriously low permeability of rock salt (a potentially negative feedback), and 2) the exposure of halite to undersaturated water released from the gypsum dehydration reaction, versus the response of the dehydration reaction to lower water activity due to dissolved salt species (a potentially positive feedback). 

Here we present insights from experiments that used time-resolved (4D) synchrotron tomographic microscopy and our x-ray transparent triaxial deformation rig Mjølnir to document the evolution of layered gypsum-halite samples that were simultaneously deformed and dehydrated. Our data, which were acquired at the TOMCAT beamline at the Swiss Light Source, allow us to visualise chemical-hydraulic-mechanical feedbacks on the grain scale, and quantify the microscale evolution of transport properties. In this contribution, we show that gypsum dehydration affects the capacity of the halite layers to retain the liberated fluids. The reaction itself generates the pore fluid pressure to create permeability in the salt layers through hydraulic fracturing. Dissolved salt significantly accelerates the reaction, and the evolving interconnected porosity facilitates the transport and precipitation of solutes, which contributes to the rheological complexity. These insights have, potentially significant, repercussions on the long-standing assumption about the significance of the gypsum dehydration on thrust fault formation within evaporitic sequences.
Eastward Propagating Second Harmonic Poloidal Waves Triggered by Temporary Outward Gradient of Proton Phase Space Density: Van Allen Probe A Observation
Authors: Yamamoto Kazuhiro , Nosé Masahito , Keika Kunihiro , Hartley David , Smith Charles , MacDowall Robert , Lanzerotti Louis , Mitchell Donald , Spence Harlan , Reeves Geoff , Wygant John , Bonnell John , Oimatsu Satoshi
Published: March 2020

Two wave packets of second harmonic poloidal Pc 4 waves with a wave frequency of ~7 mHz were detected by Van Allen Probe A at a radial distance of ~5.8 RE and magnetic local time of 13 hr near the magnetic equator, where plasmaspheric refilling was in progress. Proton butterfly distributions with energy dispersions were also measured at the same time; the proton fluxes at 10–30 keV oscillated with the same frequency as the Pc 4 waves. Using the ion sounding technique, we find that the Pc 4 waves propagated eastward with an azimuthal wave number (m number) of ~220 and ~260 for each wave packet, respectively. Such eastward propagating high‐m (m > 100) waves were seldom reported in previous studies. The condition of drift‐bounce resonance is well satisfied for the estimated m numbers in both events. Proton phase space density was also examined to understand the wave excitation mechanism. We obtained temporal variations of the energy and radial gradient of the proton phase space density and find that temporal intensification of the radial gradient can generate the two wave packets. The cold electron density around the spacecraft apogee was >100 cm−3 in the present events, and hence the eigenfrequency of the Pc 4 waves became lower. This causes the increase of the m number which satisfies the resonance condition of drift‐bounce resonance for 10–30 keV protons and meets the condition for destabilization due to gyrokinetic effect.
The BSI indicator: preventing thermal interferences between groundwater heat pump systems
Authors: García-Gil Alejandro , Marazuela Miguel Ángel , Mejías Moreno Miguel , Vázquez-Suñè Enric , Garrido Schneider Eduardo , Sánchez-Navarro José Ángel
Published: March 2020

Shallow geothermal systems are the most efficient and clean technology for the air-conditioning of buildings and constitutes an emergent renewable energy resource in the worldwide market. Undisturbed systems are capable of efficiently exchanging heat with the subsurface and transferring it to human infrastructures, providing the basis for the successful decarbonisation of heating and cooling demands of cities. Unmanaged intensive use of groundwater for thermal purposes as a shallow geothermal energy (SGE) resource in urban environments threatens the resources´ renewability and the systems´ performance, due to the thermal interferences created by a biased energy demand throughout the year. To ensure sustainability, scientifically-based criteria are required to prevent potential thermal interferences between geothermal systems. In this work, a management indicator (balanced sustainability index, BSI) applicable to groundwater heat pump systems is defined to assign a quantitative value of sustainability to each system, based on their intrinsic potential to produce thermal interference. The BSI indicator relies on the net heat balance transferred to the terrain throughout the year and the maximum seasonal thermal load associated. To define this indicator, 75 heating-cooling scenarios based in 23 real systems were established to cover all possible different operational conditions. The scenarios were simulated in a standard numerical model, adopted as a reference framework, and thermal impacts were evaluated. Two polynomial regression models were used for the interpolation of thermal impacts, thus allowing the direct calculation of the sustainability indicator developed as a function of heating-cooling ratios and maximum seasonal thermal loads. The BSI indicator could provide authorities and technicians with scientifically-based criteria to establish geothermal monitoring programs, which are critical to maintain the implementation rates and renewability of these systems in the cities.
The Role of the NECC in a Strong El Niño.
Authors: Webb David
Published: March 2020

An analysis of archived data from the NEMO 1/12th degree global ocean model shows the importance of the North Equatorial Counter Current (NECC) in the development of the strong 1982–1983 and 1997–1998 El Niños.  The model results indicate that in a normal year the coreof warm water in the NECC is diluted by the surface Ekman transport, by geostrophic inflow and by tropical instability waves. During the development of the 1982–1983 and 1997–1998 El Niños, these processes had reduced effect at the longitudes of warmest equatorial temperatures. During the autumns of 1982 and 1997, the speed of the NECC was also increased by a stronger-than-normal annual Rossby wave and other changes in sea level in the western Pacific.  The resulting increased transport of warm water by the NECC resulted in water with temperatures above 28C reaching the eastern Pacific.  This appears to have been a major factor in moving the centre of deep atmospheric convection eastwards across the Pacific.

Note:  This is based on the paper published in Ocean Science.  An oral presentation is possible.
Can we use graphene as a conversion surface for a neutral particle detector?
Authors: Grigoriev Alexander , Fedorov Andrei , André Nicolas
Published: March 2020

An important technique of modern space plasma diagnostics is a detection and imaging of low energy (below 10 keV) energetic neutral atoms (ENA). Any space mission devoted to study of the planetary plasma environments, planetary magnetospheres and heliosphere boundaries, needs a low energy ENA imaging sensor in its payload list. A common approach to the ENA detection/imaging is to make energetic neutral atoms glance a high quality conductive surface and either produce a secondary electron, or produce a positive or negative reflection ion. In the first case we can collect and detect the yielded secondary electron and generate a start signal. The reflected neutral atom can be directed to another surface with a high secondary electron yield. Thus we can measure a time-of-flight of the reflected particle to get its velocity. In the second case we can analyze the reflected ion in an electrostatic analyzer to get the particle energy.

Many types of conversion surfaces have been investigated over last decades in order to optimize an ENA sensor properties. We investigated properties of a thin layer of graphene applied to a silicon wafer surface. The experimental setup consisted of a secondary electron detector, neutral/ions separator and a high resolution particle imager. We used an incident He beam with energy of 200 eV - 3000 eV. We obtained a secondary electron emission, particle reflection efficiency, scattering properties, and a positive ion production rate as a function of the incident beam energy and the grazing angle. The experiment results show that 1) Graphene is a good source of secondary electrons even for low energy incident particles; 2) ENA scatter from the graphene surface similar to other surface types; 3) Graphene does not convert incident ENA to positive ions, especially for high grazing angles.
A Noisy Excitable Model of Millennial Scale Glacial Climate Variability
Authors: Vettoretti Guido , Ditlevsen Peter , Jochum Markus , Rasmussen Sune , Nisancioglu Kerim
Published: March 2020

The Dansgaard-Oeschger (D-O) oscillation recorded in isotopic analyses of Greenland ice cores is a climate oscillation with millennial scale variability alternating very rapidly between cold climate and warm climate states. In contrast to theories invoking Heinrich event forced oscillations or stochastic noise induced transitions between on or off states of the Atlantic Meridional Overturning Circulation, theories are emerging that propose that the D-O oscillation is an intrinsic stable glacial limit cycle relaxation oscillation that can be perturbed by internal and external forcing.  Here we use the Community Earth System Model (CESM), run with glacial boundary conditions, which accurately simulates internal unforced D-O oscillations that can be modulated by radiative forcing, freshwater forcing, and changes in ocean mixing. Based on our set of CESM climate simulations, we propose a clear process-based framework that explains the natural intrinsic timescale for the millennial scale climate transitions. We build a reduced dimensional planar dynamical system model in which the parameters of the simple model are informed by the fully coupled glacial climate model. This simple system can produce self-sustained millennial scale abrupt climate transitions, which can be modulated by forcing and display a behaviour like that observed in the complex model. We conclude that the physics underlying the glacial climate system is characterized by an excitable system susceptible to coherence resonance with similar analogues in biological systems that operate on vastly different spatial and time scales.
Linking regional modelling with field measurements to evaluate effectiveness of living windbreaks as measures against wind erosion
Authors: Weninger Thomas , King Nathan , Gartner Karl , Kitzler Barbara , Scheper Simon , Strauss Peter , Michel Kerstin
Published: March 2020

The degrading impact of wind on agricultural soils has been observed throughout centuries in the Pannonian region of central Europe. Nevertheless, soil loss was not yet quantified and the extent or relevance of the problem are unknown for this agriculturally important region. Especially dry soil surface is highly prone to erosion and as drought periods are expected to become more frequent and severe with changing climate, the risk of wind erosion will increase accordingly. Living windbreaks and similar agro-forestry systems are supposed to be highly effective measures against wind erosion. In an extensive research project, multiple approaches are integrated to obtain a broad view onto the relevance of soil degradation by wind on plot scale and its regional distribution.

More in detail, case studies are conducted where the soil loss by wind erosion is measured in sediment traps. Data about driving and stabilizing factors like wind speed, soil moisture, vegetation density etc. are measured in high spatial and temporal resolution. The measurements started in December 2019. Besides, wind erosion risk is modelled and mapped on regional scale applying state-of-the-art model procedures. The measurement results are used in an attempt to down-scale the model application and thus create a link to ground-truth data. Information about spatial and temporal variability of the driving factors is used for implementation of stochastic calculation procedures in a sensitivity study which determines the most relevant factors for wind erosion mitigation.

The used modelling approach also includes the effects of wind shelters what enables a partly evaluation of the existing network of such elements in the Pannonian region. There, the Authority of Land Reform has been supporting and documenting the installation of wind shelters for more than 60 years. Incorporating this data base, quantitative and qualitative statements will be developed about the state of the shelter belts and their relevance concerning erosion rates. Additionally, the potential and actual value of living windbreaks will be determined with special regards to physiological and ecological characteristics, stability under future climate conditions and further ecosystem services in agricultural landscapes.
The effect of the blocking of impact ocean waves by the crevasse-ridden ice shelf
Authors: Konovalov Yuri
Published: March 2020

The propagation of high-frequency elastic-flexural waves through an ice shelf was modeled by a full 3-D elastic model, which also takes into account sub-ice seawater flow. The sea water flow is described by the wave equation. Numerical experiments were undertaken both for an intact ice shelf free of crevasses, which has idealized rectangular geometry, and for a crevasse-ridden ice shelf. The crevasses were modeled as triangle/rectangular notches into the ice shelf. The obtained dispersion spectra (the dispersion curves describing the wavenumber/periodicity relation) are not continuous. The spectra reveal gaps that provide the transition from n-th mode to (n+1)-th mode. These gaps are observed both for an intact ice shelf free of crevasses and for a crevasse-ridden ice shelf. They are aligned with the minimums in the amplitude spectrum. That is the ice shelf essentially blocks the impact wave at this transition. However, the dispersion spectrum obtained for a crevasse-ridden ice shelf, has a qualitatively difference from that obtained for an intact ice shelf free of crevasses. Moreover, the dispersion spectrum obtained for a crevasse-ridden ice shelf reveals the band gap – the zone there no eigenmodes exist (Freed-Brown and others, 2012). The numerical experiments with the crevasse-ridden ice tongue that is 16 km in longitudinal extent, 0.8km width and 100m thick, were undertaken for a wide range of the periodicities of the incident wave: from 5 s to 250 s. The obtained dispersion spectra reveal two band gaps in this range: the first band gap at about 20 s and the second band gap at about 7 s for 1km spatial periodicity of the crevasses. The width of the band gap significantly increases when the crevasses depth increases too. Respectively, the amplitude spectra reveal significantly increasing area of periodicities/frequencies where the ice shelf blocks the impact wave.

References

Freed-Brown, J., Amundson, J., MacAyeal, D., & Zhang, W. (2012). Blocking a wave: Frequency band gaps in ice shelves with periodic crevasses. Annals of Glaciology, 53(60), 85-89. doi:10.3189/2012AoG60A120

Konovalov, Y.V. (2019). Ice-shelf vibrations modeled by a full 3-D elastic model. Annals of Glaciology, 1-7. doi:10.1017/aog.2019.9
Using explanatory crop models to help decision support system in controlled environment agriculture (CEA)
Authors: Amitrano Chiara , Chirico Giovanni Battista , Rouphael Youssef , De Pascale Stefania , De Micco Veronica
Published: March 2020

Lettuce (Lactuca sativa L.) is a popular leafy vegetable, widely grown and consumed throughout the world. Growing Lettuce plants in controlled environment, it is useful to increase the yield and obtain production year-round. In CEA (Controlled Environment Agriculture), computer technology is an integral part in the production and different sensors used to monitor environmental parameters and activate environmental control, are necessary. With the advent of technology, proximal sensors and plant phenotyping (in terms of physiological measurements of plant status) can help farmers in crop management. However, these kinds of tools are often expensive or inaccessible for stakeholders. The application of these tools to small-scale cultivation trials, could provide data for the implementation of mathematical models capable of predicting changes possibly happening during the cultivation. These models could then be applied at larger scales, as extensive farm production and be used to help in the cultivation management.

In this study, green and red cultivars of Lactuca sativa L. ‘Salanova’ were grown in a growth chamber under controlled environmental condition (T, RH, light intensity and quality) in two trials under different vapour pressure deficit (VPD) : 1) VPD of 0.70 kPa (Low VPD; nominal condition) and 2) VPD of 1.76 (High VPD; off nominal condition). Plants were irrigated to field-capacity and weighted every-day in order to record daily ET; infra-red measurements were carried out to record leaf temperature and pictures were taken to monitor growth during the cultivation. Furthermore, after 23 days, on fully developed leaves, eco-physiological analyses (gas exchange and chlorophyll “a” measurements) were performed to assess the plant physiological behaviour in response to the different environmental conditions. Environmental data, were used as inputs in an energy cascade model (MEC) to predict changes in the plant daily growth, photosynthesis and evapotranspiration. The original model, was implemented with a few variations: leaf temperature (T) was used in place of air T for computing the stomatal conductance (gs) and the model parameters maxCUE and maxQY, were differentiated for the nominal and off-nominal scenarios and for green and red lettuce cultivars. After the validation against experimental data, this model appears to be a promising tool that can be implemented for forecasting variations triggered by anomalies in the environmental control. However, a next step will be to add a few parameters that will consider the intrinsic morpho-physiological variability of plants during leaf development.
Evaporation from porous media as influenced by osmotic potential
Authors: Salman Adil , Joshi Deep , Naseri Mahyar , Durner Wolfgang
Published: March 2020

The measurement of the water potential is important to characterize solute transport in soil and water uptake by plants. Many researchers have characterized the matric potential and its impact on evaporation from porous media. However, only few studies have been carried out to characterize the effect of the osmotic potential. In this study, we investigated the simultaneous influences of the osmotic and matric potentials on the evaporation from soil. Our hypothesis was that both potential components affect the two stages of evaporation and that the osmotic potential in direct vicinity of the soil surface is a controlling variable. To meet our objective, we performed evaporation experiments on columns filled with pure quartz sand and natural soil materials with different textures, under climate-controlled laboratory conditions. The soils were initially saturated with different concentrations of saline solutions and evaporation from each column was measured daily. Our results show that the osmotic potential reduced the amount of evaporated water from the investigated porous media. The amount of reduction due to the osmotic potential is compared with model calculations that consider the total water potential at the soil surface.
An International Data Centre for GNSS Interferometric Reflectometry Data for Observing Sea Level Change
Authors: Matthews Andrew , Williams Simon , Bradshaw Elizabeth , Gordon Kathy , Hibbert Angela , Jevrejeva Svetlana , Rickards Lesley , Woodworth Philip
Published: March 2020

The Permanent Service for Mean Sea Level (PSMSL) is the internationally recognised global sea level data bank for long-term sea level change information from tide gauges, responsible for the collection, publication, analysis and interpretation of sea level data. The primary aim of PSMSL is to collate, archive and distribute long-term sea level information from tide gauges. There is a need both for more records in data sparse regions such as Antarctica, the Arctic and Africa, and for a low cost method for monitoring climate change through sea level.

Recent studies have demonstrated the utility of ground-based GNSS Interferometric Reflectometry (GNSS-IR) for the observation of sea level. GNSS receivers suffer from multipath, but if the physical and geometric effects multipath has on the measured signals are understood then this knowledge can be used to measure other environmental parameters such as the sea surface reflection. The GNSS receiver can also determine vertical land motion.

PSMSL has received funding to create an international archive to preserve and deliver GNSS-IR data and to integrate these data with existing sea level observing networks. We aim to create an efficient data delivery mechanism to allow the sea level community to access these new data and incorporate them into existing records. We will develop a data format and create and/or populate controlled vocabularies with the new parameters, site identifiers and other discovery metadata required.

Currently, we have processed records from over 250 GNSS receivers across the globe: each will be made available alongside information detailing how the records were processed; which GNSS constellations, satellites and frequencies were used; and visual diagnostics of each site. In this presentation we will give a brief overview of the theory behind GNSS-IR, and present some of the content that we plan to include in the completed portal.

 
Estimating current and future groundwater resources across the Cauvery basin using a macro-scale gridded water-resource model
Authors: Baron Helen , Keller Virginie , Horan Robyn , Houghton-Carr Helen , Rees Gwyn , Collins Sarah , Jackson Christopher , Mujumdar Pradeep , Muddu Sekhar , Rajendran Rajesh
Published: March 2020

Groundwater is a vital source of freshwater, an estimated 39% of all freshwater withdrawals in India are from groundwater. However, groundwater is a finite resource, and there is evidence that aquifers in Peninsular India are being depleted faster than they can recharge. This imbalance is likely to get worse in the future with the effects of a changing climate and increasing population.

It is clear that an accurate assessment of groundwater availability, now and in the future, is essential, but this is a challenge. High spatial variability coupled with the difficulty in measuring aquifer properties make it difficult to model groundwater at a basin scale. To address this, the representation of groundwater within the Global Water AVailability Assessment (GWAVA) model has been developed to provide greater insight into groundwater resources as part of an integrated water availability assessment in the Cauvery basin (81,000 km2) in Peninsula India.

For this assessment, the GWAVA model was adapted to include an improved groundwater representation, along with the effect of small-scale human interventions intended to artificially recharge groundwater. The model was calibrated against streamflow and groundwater levels across the basin. Model runs were executed for a baseline period and for future decades, using relevant combinations of CMIP5 climate (RCP) and shared socio-economic pathways (SSP) scenarios.

Over the baseline period (1986-2005), groundwater abstraction exceeded net aquifer recharge over 66% of the area of the basin. In the future (2061-2080), this was predicted to increase to 71% under the “worst-case” scenario (RCP 8.5, SSP 3) and 93% under the “best-case” scenario (RCP 4.5, SSP 1). This supports the existing evidence that groundwater resources are currently overexploited in the Cauvery basin and suggests that this situation will get worse in the future.

An additional output of this study has been to identify gaps in the data necessary for groundwater modelling (e.g. characteristics of aquifers, density of interventions, time series of aquifer levels and groundwater pumping), in terms of data availability and confidence. This knowledge can be used to inform future data collection to maximise the usefulness of future observations.

This method can be applied to other regions with a high dependency on groundwater, such as sub-Saharan Africa, for integrate water-resource assessments. It could also be extended in the future to include a water-quality component in the groundwater processes.
Improving sea-ice cover and SST forecasts by sea-ice thickness initialization
Authors: Tietsche Steffen , Balan Sarojini Beena , Mayer Michael , Zuo Hao , Vitart Frederic , Balmaseda Magdalena
Published: March 2020

A substantial amount of subseasonal-to-seasonal sea-ice variability is potentially predictable, but improved model biases and initialization techniques are needed to realize this potential. Forecasts for other Earth System components can be expected to benefit from improved sea-ice forecasts as well, because the presence of sea ice drastically alters exchanges of heat and momentum between the atmosphere and the ocean. Here, we present the impact of initializing subseasonal forecasts with observed sea-ice thickness. The newly developed sea-ice thickness data set CS2SMOS that we use is derived from radar altimetry and L-band radiance satellite observations. It allows for the first time a spatially complete view of pan-Arctic ice thickness on a near-daily basis during the freezing season. The ingestion of this data into the ECMWF ocean reanalysis system improves subseasonal forecasts of the Arctic ice edge during the melting season by up to 10%. Sea-surface temperature forecasts at high latitudes are also significantly improved during the melting season, because an improved prediction of ice-free date allows an improved forecast of the amount of seasonal warming. These results illustrate the potential for improving subseasonal-to-seasonal predictions by initializing the sea-ice thickness.
VNIR spectroscopy for assessment of post-fire impacts on soil properties using linear and non-linear calibration methods
Authors: Hrelja Iva , Šestak Ivana , Perčin Aleksandra , Pereira Paulo , Bogunović Igor
Published: March 2020

Fire is an important element of the ecosystems, nevertheless, high severity fires can have negative impacts on the ecosystems as consequence of the high temperatures reaches. High temperatures normally have detrimental impacts on soil properties. The objective of this work was to determine the relationship of spectral reflectance and soil pH, electrical conductivity (EC), carbonates (CaCO3) and total carbon (TC) content after a medium to high severity wildfire occurred in Croatia using linear and nonlinear calibration models.

Soils were sampled 2 days after a medium to high severity wildfire in Zadar County, Croatia. A total of 120 soil samples (0-5 cm) were collected from three different treatments (n= 40 per treatment): control (C), mean severity (MS), high severity (HS). Soil pH, EC, CaCO3 and TC content were determined using standard laboratory methods.  Soil spectral measurements were carried out using a portable spectroradiometer (20 per treatment, 60 in total). Linear statistical model - partial least squares regression (PLSR) and non-linear - artificial neural network (ANN) were generated to estimate changes in soil pH, EC, CaCO3 and TC content based on the original spectral reflectance and its first derivative in form of principal components (PC). One-way ANOVA revealed pH values were significantly different in all three treatments. EC, CaCO3 and TC were significantly higher in HS plots compared with the other treatments.

Different wildfire severity indicated very collinear soil spectral response, but with certain variations of reflectance intensity. Control samples showed a higher reflectance than MS and HS samples. This is attributed to the low pH and TC content. Low reflectance of MS and HS samples could be explained by their increased pH and TC values. Soil pH was the only parameter that showed a high R2 and low root mean squared error (RMSE) after Savitzky Golay smoothing and the first derivation. In PLSR model, strong to very strong correlation and low RMSE were obtained. ANN model also showed a high R2 and lower RMSE for all properties except pH. Both models showed satisfactory results for prediction of the studied soil properties. ANN model predicted EC, CaCO3, and TC better, while PLSR proved to be a better model for pH prediction.

Key words: soil reflectance, fire severity, principal components, partial least squares regression, neural networks

Acknowledgements

This work was supported by Croatian Science Foundation through the project "Soil erosion and degradation in Croatia" (UIP-2017-05-7834) (SEDCRO).
Glacier-plume or glacier-fjord circulation models? A model intercomparison for Hansbreen-Hansbukta system, Svalbard
Authors: De Andrés Eva , Otero Jaime , Navarro Francisco
Published: March 2020

 Up to 30% of the global tidewater mass loss corresponds to frontal ablation through submarine melting and calving. However, the glacier-fjord interactions remain poorly understood and challenging to constrain in the models. We have developed a 2D glacier flowline-plume coupled model that includes subglacial discharge, submarine melting and iceberg calving to simulate Hansbreen-Hansbukta system (SW Svalbard). We run the model for 20 weeks, from April to September of 2010, with weekly information exchange between glacier and plume models. The same set up and constraints of a previous glacier-fjord circulation model are used here, making the results of both simulations comparable. We consider a 200 m-width subglacial discharging channel, which was found to be a good approximation in the previous glacier-fjord model. Submarine melt rates show high sensitivity to the subglacial-discharge and ambient fjord-temperature intraseasonal evolution. Calving rates are highly dependent on both submarine melting and crevasse water depth. Glacier-plume and glacier-fjord coupled models differ in vertically-accumulated submarine melt rates (up to 30 % higher for the glacier-plume model) and show different melt-undercutting front shapes, which have an influence on the net stress fields near the glacier front. The quasi-linear melt-undercutting morphology exhibited by the glacier-plume model promotes higher calving rates than the quasi-parabolic front shape resulting from the glacier-fjord model, although both models predict similar front positions. Given that the glacier-plume model diminishes the computational cost by a factor of >50, we think that it is a good option for projection studies, as long as we apply appropriate constraints to subglacial discharge fluxes and ambient fjord temperatures.
Gigantic-thick turbidite succession in a Miocene fault-bounded trough of the South China Sea rifted continental margin: Examples from Taiwan
Authors: Li Jianyu , Lin Andrew Tien-Shun
Published: March 2020

The Loshui Sandstone, a Miocene turbidite succession accumulated in the northern slope of the rifted continental margin of the South China Sea, is exposed in the Hengchun Peninsula, Taiwan. We conduct lithofacies analysis to understand the depositional processes and mechanisms of the gigantic-thick turbidite succession.

Several features can be recognized from outcrops: (1) the Loshui Sandstone is of around 1,000 m thick with turbidite units stacked vertically; (2) high net-to-gross ratio (> 0.9) with dominant fine-to-medium grained sandstones, amalgamated beds are commonly found in the very thickly-bedded turbidites; (3) thick individual turbidite beds with a nominal thickness of 70 cm, which is thicker than classical Bouma sequence; and (4) limited deep scouring surfaces and thick mud are found. Two end-member lithofacies of high-density turbidites and low-density turbidites, respectively, are identified. High-density turbidites are thicker (more than 1 m thick) and coarser in grain size (mostly medium sands) with abundant massive intervals, dewatering structures and/or climbing ripples. Low-density turbidites tend to be thinner in thickness and finer in grain size (mostly fine sands) with parallel bedding and/or normal ripples. In addition to the above two lithofacies, chaotic deposits of mass transport deposits (MTDs) are also widespread within the studied succession.

Sand-rich, vertically aggrading succession, but lack of deep-scouring surfaces and levee deposits, indicates that turbidites are laid down by unconfined turbidity currents in a sand-rich deepwater lobe. In addition, gigantic thick turbidite unit stacked continuously up to 1,000 m, implying that the lobe is confined within a rapidly subsiding basin. We interpreted that the Loshui Sandstone is vertically stacked and accumulated within a fault-bounded trough in the deepwater area of the rifted continental margin of the South China Sea.

 