bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Validation and Assimilation of Aeolus Wind Observations
Authors: Martin Anne , Geiss Alexander , Cress Alexander , Weissmann Martin
Published: March 2020

The earth explorer mission Aeolus from the European Space Agency for the first time worldwide opens up the possibility to directly observe Earths’ wind profiles from space. Aeolus carries a Doppler wind lidar operating at 335 nm which measures the Doppler frequency shift of backscattered laser light from air molecules and particles up to 30 km accumulated in 0.25 - 2 km vertical range bins. It’s expected that such global coverage of wind profiles helps to fill a gap in the global observing system.

As part of the German initiative EVAA (Experimental Validation and Assimilation of Aeolus observations) validation and monitoring activities for Aeolus are performed to determine and understand observation systematic and random errors. Independent ground-based measurements from radiosondes and tropospheric radar wind profilers are used as reference for the evaluation of Aeolus winds. In addition monitoring results from the global model ICON from the German Weather Service (DWD) are used to examine the results and investigate bias dependencies. An accurate understanding of the systematic errors of Aeolus wind observations is necessary for data assimilation processes. First impact experiments with an established bias correction for Aeolus wind data were run at DWD showing encouraging results for forecast improvements in upper tropospheric and lower stratospheric tropics and southern hemisphere.
In situ evidence of firehose instability in multiple magnetic reconnection
Authors: Alexandrova Alexandra , Retinò Alessandro , Divin Andrey , Matteini Lorenzo , Le Contel Olivier , Breuillard Hugo , Catapano Filomena , Cozzani Giulia , Deca Jan
Published: March 2020

Energy conversion via reconnecting current sheets is common in space and astrophysical plasma. Frequently, current sheets disrupt at multiple reconnection sites, leading to the formation of plasmoid structures between the sites, which might affect energy conversion. We present in situ observations of multiple reconnection in the Earth’s magnetotail. The observed highly accelerated proton beams parallel to magnetic field and the ion-scale wave-like fluctuations of the whistler type imply the development of firehose instability between two active reconnection sites. The linear wave dispersion relation estimated for the measured plasma parameters, indicates a positive growth rate of the firehose-related electromagnetic fluctuations. The detailed time-space evolution of the plasmoid is obtained by reconstruction of observations with the 2.5D implicit particle-in-cell simulations. In course of time, plasma on the periphery of the plasmoid becomes anisotropic and as it overcomes the firehose marginal stability threshold, the corresponding magnetic field fluctuations arise. The results of observations and simulations suggest that the firehose instability operating between reconnection sites, converts plasma energy of the proton temperature anisotropy to the energy of magnetic field fluctuations, counteracting with the conversion of magnetic energy to the energy of plasma in reconnection sites.
Validation of the S5P Formaldehyde L2 product using MAX-DOAS network observations
Authors: De Smedt Isabelle , Pinardi Gaia , Vigouroux Corinne , Compernolle Steven , Eichman Kai Uwe , Langerock Bavo , Lerot Christophe , Theys Nicolas , Vlietinck Jonas , Yu Huan , Romahn Fabian , Hedelt Pascal , Cheng Zhibin , Lambert Jean-Christopher , Loyola Diego , Van Roozendael Michel ,   NIDFORVAL HCHO team
Published: March 2020

The Sentinel-5 Precursor (S5P) was launched on the 13th of October 2017, with on board the TROPOspheric Monitoring Instrument (TROPOMI). The formaldehyde (HCHO) L2 product is operational since the end of 2018. The prototype of the tropospheric HCHO retrieval algorithm is developed at BIRA-IASB and implemented at the German Aerospace Center (DLR) in the S5P operational processor (De Smedt et al., 2018).

In this work, we investigate the quality of the HCHO tropospheric column product and its validation within the MPC framework (Mission Performance Center) and the S5PVT NIDFORVAL project (S5P NItrogen Dioxide and FORmaldehyde VALidation). Within NIDFORVAL, the S5P HCHO product has been validated using the full FTIR and MAXDOAS dataset. Validation results have been assessed against reported product uncertainties taking into account the full comparison error budget, showing that the product quality reaches its requirements.

Here, we focus on satellite-satellite comparison based on the OMI QA4ECV HCHO product and on ground-based validation using MAX-DOAS and Pandora network observations. About 15 HCHO measuring stations are involved, providing data corresponding to a wide range of observation conditions at mid and low latitudes, and covering remote, sub-urban, and urban polluted sites. Comparison results show usually negative biases for large HCHO columns, while a positive offset is observed for the lowest columns. For the MAX-DOAS stations providing vertical profile retrievals, the impact of a priori profiles on the comparison is assessed. The dataset allows to discuss validation results as a function of emission source. Seasonal and diurnal variations are compared. Long term variation are also monitored using the OMI and MAX-DOAS QA4ECV dataset.
Expo-Laboratory: a learning path based on direct experience and peer education
Authors: Christille Claretta , Occhipinti Susanna
Published: March 2020

The teaching of experimental sciences requires continuous updating and needs of tools – laboratories, materials, experimental protocols – that promote the acquisition of the experimental scientific method, through the individual practice of operating procedures that allow personal and direct consolidation and experimental verification of theoretical knowledge.

Now in its 16th edition, the Expo-laboratory is a learning path of several exhibits, proposed annually in Aosta Valley (Italy), involving different schools and dealing each year with a different topic.

The exhibition, created with the collaboration of several teachers, is aimed at students from kindergarten to high school, with the aim of presenting scientific aspects both in a theoretical and practical way, through simple tools, experiments or practical demonstrations that can be easily repeated.

This year the exhibition, entitled "The Science of Wonders", proposes a learning path made by tools and short impressive activities dealing with history and theory of some surprising topics, ranging from chemical sciences to biological, geological and physical ones.

The peculiarity of Expo-Laboratory is that the illustration of each exhibit is carried out by students, who are called to accompany visitors to discover the various activities, by adapting the content in relation to the age and the interest of the public.

The Expo-Laboratory presents itself as a real experience of peer learning and teaching and, over the years, it has shown good educational effects, offering students an opportunity to acquire new knowledge, develop scientific communication skills and increase organizational abilities through cooperation and collaboration.

The experience is generally appreciated by students who, operating with simple materials, but with scientific rigor, have the chance to get really involved. Playing a role they are not used to (the teacher’s one), they have to deal with a heterogeneous audience, sometimes curious and demanding, other times distracted, so they need to test and improve their own engagement abilities, face follow-up questions and provide further explanations. All this, not only enhances their sense of responsibility, but also boosts self confidence and personal skills, definitely stimulating passion and students' interest in sciences.
Multiplet Based Time Lapse Velocity Changes Prior to the 2018 Eruption of Sierra Negra Volcano, Galapagos Island Observed with Coda Wave Interferometry
Authors: Longobardi Mariantonietta , Grannel James , Bean Christopher , Bell Andrew , Ruiz Mario
Published: March 2020

Changes in external stress state and fluid content alter the mechanical properties of an geological media. Variations in seismic wave velocity can be used as proxies for changes in stress the onset of mechanical demage and/or possible fluid ingression. Temporal variations in seismic wave velocity have previously been monitored and observed prior to volcanic eruptions. In the absence of additional constraints related to stress or fluid changes on the volcano, these pre-eruptive changes are difficult to interpret and hence the causes of them are often not well understood. In this study, Coda Wave Interferometry (CWI) is used to measure time-lapse changes in seismic velocity on seismic multiplets (repeating similar earthquakes). In particular, we focus our analysis on using this technique to calculate the velocity changes on the data recorded prior to the 2018 eruption of Sierra Negra volcano, Galapagos Island. On 26th June 2018 at 09:15 UTC, a magnitude 5.3 earthquake occurred near the south-west caldera rim and an intense seismic swarm started around 17:15 UTC. Seismic tremor dominated at about 19:45 UTC, which marked the onset of the eruption. A very large seismicity sequence preceded the eruption. The pricise relationship between the magnitude 5.3 event and the eruption is not fully constraind. Here we search for multiplets in order to achieve high time resolution velocity change information in the hours between the large earthquake and the eruption. Our aim is to understand whether changes in seismic velocity measured with CWI on multiplets method provide new insight into the physical processes related to the eruption.
Landslides in Central Italy identified from Sentinel 2 multispectral imaging time series analysis with Google Earth Engine
Authors: Bartola Marco , Braitenberg Carla , Bisci Carlo
Published: March 2020

In 2016, Central Italy was hit by a months-lasting earthquake sequence that started off in August 24th 2016 with a Mw 6.2 earthquake which provoked severe damage to the towns of Accumoli (RI) and Amatrice (RI). The following October 30th 2016 earthquake (Mw 6.5), with epicenter in Norcia (PG) about 20 km NW of the first shock, triggered landslides in the area of Visso (MC), as reported by local newspapers.

The purpose of this work is to individuate the areas affected by such landslides using the radiance variation recorded by multispectral images acquired by Sentinel 2. The time series analysis of the images has been carried out in Google Earth Engine environment, that allows access to the entire suite of available images. Due to the steep terrain, the shadowing effect of the hills was taken into account and comparison of images have been made only for those taken in the same seasonal moment of different years, thus guaranteeing the same solar elevation.

It was found that the band of red was instrumental in identifying landslides along slopes made up of limestone, which is the typical outcrop of the area. Due to the extended time period between the images (July 2015 and July 2017), anthropogenic changes in land-use were present and had to be distinguished from landslides. A criterion involving the slope angle was developed, maintaining only the changes that had occurred on slopes steeper than 25°, since man-made interventions giving similar spectral response are hardly done in steep areas. The slope analysis and correlation study with the extension and location of landslides was carried out using a Geographic Information System. (ESRI ArcGIS 10.5) The total extent of the area affected by the surveyed landslides is very large, having  been estimated to be more than 200 000 m2.
Sensitivity of the Atlantic Meridional Overturning Circulation to Model Resolution in CMIP6 HighResMIP Simulations
Authors: Iovino Dorotea , Roberts Malcolm J. , Jackson Laura C. , Roberts Christopher D. , Meccia Virna , Docquier David , Koenigk Torben , Ortega Pablo , Moreno-Chamarro Eduardo , Bellucci Alessio , Coward Andrew , Drijfhout Sybren , Exarchou Eleftheria , Gutjahr Oliver , Hewitt Helene , Lohmann Katja , Schiemann Reinhard , Seddon Jon , Terray Laurent , Xu Xiaobiao ,   iHESP group members
Published: March 2020

The Atlantic Meridional Overturning Circulation (AMOC) is a key component of the three-dimensional ocean circulation that transports warm and salty water northward, and exports cold and dense water from the Arctic southward.

The simulated AMOC in Coupled Model Intercomparison Project models (both coupled and ocean-only) has been studied extensively. However, correctly simulating the AMOC with these models remains a challenge for the climate modelling community. One model aspect that can affect the AMOC representation is the model resolution (i.e. grid spacing).

Here, we examine key aspects of the North Atlantic Ocean circulation using a multi-model, multi-resolution ensemble based on the CMIP6 HighResMIP coupled experiments. The AMOC and associated heat transport tend to become stronger as model resolution increases, particularly when the ocean resolution changes from non-eddying to eddy-present and eddy-rich. However, the circulation remains too shallow compared to observations for most models, and this, together with temperature biases, cause the northward heat transport to be too low for a given overturning strength.

In the period 2015-2050, the overturning circulation tends to decline more rapidly in the higher resolution models by more than 20% compared to the control state, which is related to both themean state and to the subpolar gyre contribution to deep water formation. The main part of the decline comes from the Florida Current component of the circulation.
Corner Reflectors for Validation of Ice Flow Velocity Derived from SAR Images along the CHINARE-Route in Antarctica
Authors: Qiao Gang , Li Rongxing , Hao Tong , Tong Xiaohua , Li Yanjun , Li Hongwei , Liu Shuang , Liu Shijie , Li Yuansheng , Dou Yinke
Published: March 2020

Ice flow velocity is an important parameter for evaluating the stability of Antarctic ice shelves and analyzing the mass balance of the ice sheet. Large scale ice flow maps can be produced from satellite images with ground control and validation. Among various ground targets, corner reflectors show distinct intensity characteristics on SAR images due to its highly reflective surface shape and have been used for calibration and validation. This paper focuses on design and implementation of a set of corner reflectors to obtain the first-hand data of in-situ ice flow velocity for SAR image based ice velocity maps. The results should further help evaluate mass balance changes in East Antarctica using the input-output method.

Generally, the remote sensing method uses airborne or satellite optical and radar images from multiple periods to map ice flow velocity fields. The ground truth data are often sparse due to the harsh environment in the polar region. The annual Chinese Antarctic Research Expedition (CHINARE) makes it possible to obtain period field data of ice velocity within its campaign regions. The ~1200 km CHINARE-Route runs from Zhongshan Station to Kunlun Station along which the ice flow velocity varies from a few meters per year to 100s meters per year. 5 corner reflectors have been designed and installed along the 31st CHINARE-Route in 2015 and the 35th CHINARE-Route in 2019 (M1, M2 and M3 in the 31st CHINARE, A1and A2 in the 35th CHINARE). The ice flow velocities at the installation locations are of different orders of magnitude, about 44 m per year at the locations of M1 and A1, 93 m per year at M2 and M3 and 73 m per year at A2. The satellite orbit inclination, incident angle and the installation location were used to calculate the azimuth and elevation angles of the corner reflectors for installation. At all reflector locations GPS positions were collected at the time of installation. After that, the second time GPS coordinates of M3 in the 34th CHINARE in 2018, the third time GPS coordinates of M3, the second time GPS coordinates of A1 and A2 in the 36th CHINARE at the end of 2019 were measured respectively. TerraSAR-X was used to image the reflectors.

The results show that the mean in-situ ice flow velocity of M3 is 96.83 m per year between Feb. 2015 and Dec. 2019, with 97.51 m per year between Feb. 2015 and Jan. 2018 and 95.81m per year between Jan. 2018 and Dec. 2019. The in-situ ice flow velocity is 54.9 m per year at A1 between Jan. 2019 and Dec. 2019 and 86.92 m per year at A2 between Feb. 2019 and Dec. 2019. More TerraSAR-X and COSMO-SkyMed data will be used to extract the ice velocity corresponding to GPS measurements. The detailed information will be presented at the meeting.
On the influence of soil moisture on intra-annual peat soil dynamics as observed from SAR amplitude and phase data
Authors: Bentvelsen Falco , Heuff Floris , Steele-Dunne Susan , Wagner Wolfgang , Quast Raphael , Hanssen Ramon
Published: March 2020

Polders in the western Netherlands are often covered by pastures. Around 30 percent of the pastures are situated on peat soils, which are artificially drained. Consequently, the exposure to oxygen leads to a decomposition (oxidation) of the material and desiccation leading to shrinking. This results in a decadal subsidence, up to a few centimeters per year, which causes increasingly severe socio-economic impact. However, this long-term subsidence signal has a high spatial variability due to local soil morphology, and possibly high intra-annual temporal variability which is caused by precipitation and evaporation. The problem is that there are currently no geodetic methods that can reliably measure these soil dynamics over wide areas and with high temporal revisits.

Here we show how Sentinel-1 SAR interferometry (InSAR) can potentially be used to estimate the surface displacements, given prior information on precipitation and temperature. We observe intra-annual dynamics of surface elevation which seem to be one order of magnitude stronger than the decadal long-term subsidence. InSAR surface elevation measurements show  discontinuities (hysteresis) in late summer and early autumn due to strong vegetation and changes in temperature and precipitation patterns. As soil moisture variability appears to be the main driving mechanism for the observed surface elevation dynamics, we investigate whether we can use the amplitude of the identical SAR acquisitions to estimate the soil moisture directly, to reduce the dependency on external precipitation and temperature data.

The analysis is performed on time series of the European Space Agency’s Sentinel-1 mission. Subsidence and upheaval are estimated using a novel InSAR algorithm, which was specially designed for peat soil dynamics. The surface elevation dynamics are compared to surface soil moisture estimates from Sentinel-1 amplitude  data. Soil moisture is retrieved from backscatter time series using a first-order radiative transfer model (RT1) developed at TU Wien. This model describes the scattering behaviour of both soil- and vegetation by using linear combinations of idealized scattering distribution functions. Clay Soil swelling and subsidence are likely influenced by soil layers much deeper than those associated with the surface soil moisture estimates. Therefore, the subsidence estimates are also compared to Soil Water Index (SWI) derived from the surface soil moisture product. This is considered an indicator of moisture availability in the top 100 cm. These results show that the same complex SAR data acquisitions can be used simultaneously, but independently, for estimating soil moisture and for estimating surface elevation dynamics. An integrated application is proposed and evaluated for further exploration.
Distribution of benthic foraminifera upstream of the Elbe Estuary (Northern Europe): ecological interactions
Authors: Francescangeli Fabio , Milker Yvonne , Armynot du Châtelet Eric , Schmiedl Gerhard
Published: March 2020

Estuaries are transitional ecotones influenced by both marine and terrestrial (fresh) waters. For the past 200 years, estuarine environments experienced intense and rapid environmental degradations due to anthropogenic action (e.g., urban sewage, industry, aquaculture, and agricultural runoff). The distribution of benthic foraminifera in estuarine areas is the result of complex interactions between a large number of biotic and abiotic parameters. The natural stress (such as variation in salinity, sediment size, organic load) may be associated to anthropogenic stresses, enhancing the high natural variability of these areas. The objectives of the present work are to describe the specific composition of benthic foraminifera and to investigate their ecological interactions upstream of the Elbe Estuary (Germany). In this important estuarine area, there is a lack of a comprehensive investigation in terms of benthic foraminifera. So far, the ecology of living benthic foraminifera has not been studied in greater detail and it is largely unknown which species occur in this transitional area. For this purpose, a surface sampling was carried out from 24 stations along the salinity gradient of the Elbe Estuary. Living and dead foraminiferal assemblages were analyzed and the relative correlation with environmental parameters (such as salinity, pH, temperature, sediment size, organic matter) was investigated. Living assemblages are characterized by very low densities and largely dominated by “Ammonia” group. Dead assemblages are more diverse and dominated by estuarine taxa (Ammonia aomoriensis, Haynesina germanica, and Cribroelphidium selseyense). Upstream of the estuarine area, the low salinity prevents the development of living benthic foraminifera while downstream, sediment grain size seems to be a major key-factor, influencing foraminiferal distributions. This work sheds new light on benthic foraminiferal ecology and biodiversity of this important estuarine area of Northern Europe.
Comparison of Airborne Peroxy Radical Measurements with MECO(n) model simulation during EMeRGe in Europe
Authors: Liu Yangzhuoran , Mertens Mariano , Andrés Hernández Maria Dolores , George Midhun , Nenakhov Vladyslav , Kerkweg Astrid , Jöckel Patrick , Burrows John P.
Published: March 2020

Observations of tropospheric peroxy radicals are a key point for interpretation of the processing and transformation of polluted outflows from major populated centres (MPCs). A series of European MPCs are investigated by the project EMeRGe (Effect of Megacities on the transport and transformation of pollutants on the Regional and Global scales). With this objective two airborne campaigns using the research platform HALO (High Altitude and LOng range aircraft) were carried out over Europe in summer 2017 and over east Asia in the intermonsoon period in 2018. The Institute of Environmental Physics (IUP) in Bremen (Germany) participated in both EMeRGe campaigns with the airborne measurement of the total sum of peroxy radicals, RO2*, by using  the home made PeRCEAS instrument based on the combination of the PERCA (peroxy radical chemical amplification)  and CRDS (cavity ring down spectroscopy) techniques. One of the main purposes of the campaigns was the investigation of the characteristics and chemical transformation of MPC outflows at the local and regional scales.

During the EMeRGe campaign in Europe, air masses of different photochemical activity were measured, where RO2* mixing ratios up to 100pptv being observed. In the present study the RO2* observations for six measurement flights of EMeRGe in Europe have been compared with RO2 (here defined as the sum of HO2 + CH3O2 + ISOOH + CH3CO3 + CH3COCH2O2) simulated by using the MECO(n) model.

MECO(n) (MESSy-fied ECHAM and COSMO models nested n times), is  a global/regional chemistry-climate model developed by the MESSy consortium, which couples on-line the global chemistry-climate model EMAC with the regional chemistry-climate model COSMO-CLM/MESSy. The same anthropogenic emission inventory (EDGAR 4.3.1) as well as the same solver for chemical kinetics, involving complex tropospheric and stratospheric chemistry, are applied in EMAC and COSMO-CLM/MESSy.

Overall, the agreement between the measurements and model is reasonable for RO2* observations below 40 pptv. Events with higher mixing ratios seem not to be well reproduced by the model but underestimated. Further details on the modelling and the result of the comparison will be presented.
Hydrofractures and crustal-scale fluid flow
Authors: Bons Paul D. , de Riese Tamara , Gomez-Rivas Enrique , Naaman Isaac , Sachau Till
Published: March 2020

Fluids can circulate in all levels of the crust, as veins, ore deposits and chemical alterations and isotopic shifts indicate. It is furthermore generally accepted that faults and fractures play a central role as preferred fluid conduits. Fluid flow is, however, not only passively reacting to the presence of faults and fractures, but actively play a role in their creation, (re-) activation and sealing by mineral precipitates. This means that the interaction between fluid flow and fracturing is a two-way process, which is further controlled by tectonic activity (stress field), fluid sources and fluxes, as well as the availability of alternative fluid conduits, such as matrix porosity. Here we explore the interaction between matrix permeability and dynamic fracturing on the spatial and temporal distribution of fluid flow for upward fluid fluxes. Envisaged fluid sources can be dehydration reactions, release of igneous fluids, or release of fluids due to decompression or heating.

 

Our 2D numerical cellular automaton-type simulations span the whole range from steady matrix-flow to highly dynamical flow through hydrofractures. Hydrofractures are initiated when matrix flow is insufficient to maintain fluid pressures below the failure threshold. When required fluid fluxes are high and/or matrix porosity low, flow is dominated by hydrofractures and the system exhibits self-organised critical phenomena. The size of fractures achieves a power-law distribution, as failure events may sometimes trigger avalanche-like amalgamation of hydrofractures. By far most hydrofracture events only lead to local fluid flow pulses within the source area. Conductive fracture networks do not develop if hydrofractures seal relatively quickly, which can be expected in deeper crustal levels. Only the larger events span the whole system and actually drain fluid from the system. We present the 10 square km hydrothermal Hidden Valley Mega-Breccia on the Paralana Fault System in South Australia as a possible example of large-scale fluid expulsion events. Although field evidence suggests that the breccia formed over a period of at least 150 Myrs, actual cumulative fluid duration may rather have been in the order of days only. This example illustrates the extreme dynamics that crustal-scale fluid flow in hydrofractures can achieve.
Use of leaf hyperspectral data and different regression models to estimate photosynthetic parameters (Vcmax and Jmax) in three different row crops
Authors: Buchaillot Maria Luisa , Soba David , Shu Tianchu , Juan Liu , Araus José Luis , Kefauver Shawn C. , Sanz-Saez Alvaro
Published: March 2020

By 2050 future global food demand is projected to require a doubling of agricultural output, and climate change will exacerbate this challenge by intensifying the exposure of field crops to abiotic stress conditions, including rising temperature, increased drought, and increased CO2 concentration ([CO2]). One of the keys to improving crop yield under different stresses is studying is photosynthesis. Photosynthetic parameters, such as the maximum rate of carboxylation of RuBP (Vc,max), and the maximum rate of electron transport driving RuBP regeneration (Jmax) vary in response to climate conditions and have been identified as a target for improvement. However, the techniques used to measure these physiological parameters are very time consuming, ranging from 30 to 70 min per measurement and require specialized personnel. Therefore, breeding or genetic mapping for these traits under these conditions is prohibitively time-consuming. Spatial and temporal variation in plant photosynthesis can be estimated using remote sensing-derived spectral vegetation indices. Spectral estimates of green vegetation biomass and vigor, including vegetation indices such as the Normalized Difference Vegetation Index (NDVI), are widely used to estimate vegetation productivity across spatial and temporal scales but are unable to provide assessments of specific photosynthetic parameters. For that reason, hyperspectral remote sensing shows promise for predicting photosynthetic capacity based on more detailed leaf optical properties. In this study, we developed and assessed estimates of Vcmax and Jmax through four different advanced regression models: PLS, BR, ARDR, and LASSO based on leaf reflectance metrics measured with an ASD FieldSpec4 Hi-RES of different crops under different environmental conditions such as (1) different varieties of soybean under high [CO2] and high temperature, (2) different varieties of peanut under drought stress and (3) 20 varieties of cotton diverse origin and grown under field conditions. Both phenotypic variability and varying levels of stress were employed with each crop to ensure adequate ranges of responses. Model sensitivities were assessed for each crop and treatment separately and in combination in order to better understand the strengths and weaknesses of each model in all the different conditions. For the combination of three species, all the models suggest a robust prediction of Vcmax around R2:0.67 and the same for the Jmax R2: 0.55.
Validation of IVINE crop growth model using MACSUR2 project measurements in a few European vineyards.
Authors: Cassardo Claudio , Andreoli Valentina , Spanna Federico
Published: March 2020

The numerical crop growth model IVINE (Italian Vineyard Integrated Numerical model for Estimating physiological values) was originally developed at the dept. of Physics, Univ. of Torino, as a research model with the aim to simulate grapevine phenological and physiological processes. Since vines are generally strongly sensitive to meteorological conditions, the model should be able to evaluate the environmental forcing effects on vine growth and, eventually, on its production. IVINE model requires a set of hourly meteorological and soil data as boundary conditions; the more relevant input for the model to correctly simulate the plant growth are: air temperature and soil moisture. Among the principal IVINE outputs, we mention: the main philological stages (dormancy exit, bud-break, fruit set, veraison, and harvest), the leaf development, the yield, the berry sugar concentration, and the predawn leaf water potential. The IVINE requires to set some experimental parameters depending on the cultivar; at present, IVINE is optimized for Nebbiolo and other common varieties (such as, for example, cvs. Barbera, Vermentino, Cannonau, etc for Italy), but validation experiments have been performed only for Nebbiolo variety, due to the difficulty to gather all required measurements useful to drive the model and to compare its outputs for several consecutive years in the same vineyard. In the frame of the second part of the EU JPI-FACCE project named MACSUR (Modelling European Agriculture with Climate Change for Food Security), some data relative to vineyards displaced in several European countries were made available, thus we tried to execute simulations with IVINE in those vineyards. Since input data required by IVINE were not all present, we decided to extract input data from the international GLDAS database in the nearest grid point to the experimental vineyard, and to run the trusted land surface model UTOPIA on those points in order to evaluate soil variables required by IVINE. The main results obtained by those simulations, as well as the few possible validations with experimental observations, will be shown and commented. As a summary, we can say that the simulation carried out with IVINE seems able to well account for the interannual variability of the meteorological conditions, and the used settings seems able to allow a sufficiently valid simulation of the pheno-physiological conditions of the vineyards, but the approximation in the input data causes departures larger than if local measurements would be used.
Modelling the Rebuilding the Radiation Belt Following a Drop-out Event from Acceleration of the Seed Population
Authors: Allison Hayley , Shprits Yuri , Glauert Sarah , Horne Richard , Wang Dedong
Published: March 2020

The Earth’s electron radiation belts are a dynamic environment and can change dramatically on short timescales. From Van Allen Probes observations, we see storm time drop-out events followed by a rapid recovery of the electron flux over a broad range of energies. Substorms can supply a seed population of new electrons to the radiation belt region, which are then energised by a number of processes, rebuilding the belts. However, how the electron flux is replenished across energy space, and the sequence of events leading to flux enhancements, remains an open question. Here we use a 3-D radiation belt model to explore how the seed population is accelerated to 1 MeV on realistic timescales, comparing the output to Van Allen Probes observations. By using a low energy boundary condition derived by POES data we encompass the whole radiation belt region, employing an open outer boundary condition. This approach isolates the contribution of seed population changes and allows electron flux variations over a broad range of L* to be studied. Using the model, we explore the contribution of both local acceleration and radial diffusion and demonstrate that the timing and duration of these two processes, particularly in relation to one another, is important to determine how the radiation belt rebuilds.
Towards elaboration of a surface mass balance model of a mountain glacier using a stochastic weather generator
Authors: Dymova Taisiya , Rybak Oleg , Popovnin Viktor
Published: March 2020

Mathematical modeling of surface mass balance (SMB) of mountain glaciers requires appropriate climatic forcing. Normally, meteorological records from the weather stations located as close as possible to the glacier are used for this purpose. In the ideal case, a weather station is located directly on the glacier. Even then, weather records are comparatively short and are hardly applicable for transient simulation of glacier dynamics. Thus, the lack of observations is an obvious obstacle for obtaining reliable simulation results. To overcome it, we suggest to apply a simple stochastic weather generator to emulate synthetic records of surface air temperature, precipitation and other meteorological variables required for calculation SMB by an energy-balance model.

Weather generators have been applied in many geophysical applications for decades, except, paradoxically, for glaciological ones. This is a powerful tool enabling generation of synthetic records which are statistically similar to observations (including probability distribution, standard deviations, autocorrelations etc.).

We report about the work in progress, which aims at elaboration of a reliable methodology for SMB calculation in diverse environmental conditions.

The study was supported by Russian Foundation of Basic Research RFBR (grant Nos. 18-05-00420 and 18-05-60080).
Heavily data-constrained mechanistic ecohydrological modeling can guide management of pre-Alpine grasslands in the present and future climate
Authors: Botter Martina , Zeeman Matthias , Burlando Paolo , Fatichi Simone
Published: March 2020

The pressure of climate change and increasing food demand on agricultural systems made management strategies crucial for matching the production goals without affecting water quantity and quality. This is, for instance, the case for managed grasslands in the Alpine and pre-alpine regions. This study combines a large suite of observations from the TERENO observatory and ScaleX campaigns with mechanistic modeling, in order to analyze the response of managed grasslands north of the Alps to different climatic conditions and management strategies, aimed at evaluating changes in the ecohydrological response, as well as carbon, water and nutrient fluxes.  

First, we used the data to evaluate the performance of the mechanistic Tethys-Chloris (T&C) model, which fully integrates the solution of surface energy balance and hydrological budget with vegetation dynamics and soil biogeochemistry, for the period 2012-2016. This is characterized by significant climatic inter-annual variability and including the extraordinarily warm year 2015. The observations cover three different grassland sites composed by flux towers, soil moisture and temperature probes, lysimeters, nutrient leaching and dedicated vegetation sampling campaigns, allowing an unprecedented validation opportunity of model skills for multiple variable and temporal scales. The observed system response, in terms of water, energy and nutrients dynamics, are successfully reproduced, which increases confidence on the model capability to reproduce the feedbacks among hydrology, vegetation growth and soil biogeochemistry. The results highlight the impact of an early begin of the growing season on the vegetation productivity and nutrients leaching in years with reduced snow cover,  as well as the effects of summer drought on vegetation productivity.

Second, numerical experiments are used to test the response of this ecosystem to different grassland fertilization and cutting scenarios in the present climate and in warmer and CO2 enriched conditions. Of particular interest are the number and timing of grass cuts and fertilizer applications that could optimize grassland productivity without compromising water quality in a warmer climate.
Do heavily degraded soil really sequester carbon faster? Can that be change for soil restoration?
Authors: Frouz Jan
Published: March 2020

Soil carbon storage is crucial for global carbon budget and at the same time affect many key ecosystem functions. There are several studies showing that in initial soil substrates and or degraded soils with little overall soil organic matter content have high ability to sequester carbon. Mechanisms that cause this fast SOM sequestration are not completely elucidated but most likely arise from availability of vacant spaces where SOM can be bound by various mechanism and set of positive feedback loops which cause that increase in one SOM pool may increase rate of saturation in other pools. There are also some indication that major mechanisms how the SOM its stored in soil vary along soil development gradient. In Initial soils there may be high rate of SOM sequestration achieved under fast growing plants producing easily available litter, in this stage incorporation POC in mineral matrix, storing microbial neuromas and activity of earthworms play crucial role in SOM sequestration. While in latter stages of soil development, when soil is already close to saturation slow growing plants, producing slow decomposing litter result in higher carbon sequestration, ir seems to be that shift of microbial necromass to fungal rather than bacterial necromass, and difference in litter and microbial necromass decomposability may play important role in this stage. Implication of these finding for ecosystem restoration is discussed. 
Immersive Flooding Event Simulation for Climate Resilience Analysis
Authors: Jiang Yang , Alza Santos Joan , Wang Chen , Mabon Leslie
Published: March 2020

Immersive Technology has been widely discussed in various applications; the development of this technology creates an experience which is not possible in our physical reality. The rapid development of computer software and hardware makes the 3D visualisation and simulation of real-world scenarios could be represented in much higher resolutions. Recent studies show that visualising natural disasters immersively could be beneficial to increase people’s awareness and prepare the public for future event. In a recent research project, we visualized and simulated a flooding event, Storm Frank, in 2015 and its damage to the local residence of a town called Ballater outside Aberdeen, UK on Virtual Reality form. To provide accurate simulation, topographic data and real-world environmental data such as weather, rainfalls, river level data etc., are applied and analysed in this project. This immersive experience provides significant opportunities for effective communication among all users. The project used 3D modelling and simulation of the flooding encompasses the development and exemplification of the model of the town and real scenario flooding event, retrieving data from various sources such as geographical data and environment data. The gamification of this application shows great potential to be used for public engagement event, policy making and educational purposes. 
AmazonFACE – Assessing the response of Amazon rainforest functioning to elevated atmospheric carbon dioxide concentrations
Authors: Rammig Anja , Fleischer Katrin , Garcia Sabrina , Martins Nathielly , Menezes Juliane , Fuchslueger Lucia , Schaap Karst , Pereira Iokanam , Takeshi Bruno , Quesada Carlos , Kruijt Bart , Norby Richard , Araujo Alessandro , Domingues Tomas , Grams Thorsten , Hartley Iain , De Kauwe Martin , Hofhansl Florian , Lapola David
Published: March 2020

The rapid rise in atmospheric CO2 concentration over the past century is unprecedented. It has unambiguously influenced Earth’s climate system and terrestrial ecosystems. Elevated atmospheric CO2 concentrations (eCO2) have induced an increase in biomass and thus, a carbon sink in forests worldwide. It is assumed that eCO2 stimulates photosynthesis and plant productivity and enhances water-use efficiency – the so-called CO2-fertilization effect, which may provide an important buffering effect for plants during adverse climate conditions. For these reasons, current global climate simulations consistently predict that tropical forests will continue to sequester more carbon in aboveground biomass, partially compensating human emissions and decelerating climate change by acting as a carbon sink. In contrast to model simulations, several lines of evidence point towards a decreasing carbon sink strength of the Amazon rainforest. Reliable predictions of eCO2 effects in the Amazon rainforest are hindered by a lack of process-based information gained from ecosystem scale eCO2 experiments. Here we report on baseline measurements from the Amazon Free Air CO2 Enrichment (AmazonFACE) experiment and preliminary results from open-top chamber (OTC) experiments with eCO2. After three months of eCO2, we find that understory saplings increased carbon assimilation by 17% (under light saturated conditions) and water use efficiency by 39% in the OTC experiment. We present our main hypotheses for the FACE experiment, and discuss our expectations on the potential driving processes for limiting or stimulating the Amazon rainforest carbon sink under eCO2. We focus on possible effects of eCO2 on carbon uptake and allocation, nutrient cycling, water-use and plant-herbivore interactions, which need to be implemented in dynamic vegetation models to estimate future changes of the Amazon carbon sink.
Preliminary identification of groundwater drought events in unconfined aquifer with standardized drought indices in single multilevel groundwater station
Authors: Bikše Jānis , Kalvāns Andis , Retike Inga , Babre Alise , Popovs Konrāds , Dēliņa Aija
Published: March 2020

More severe and frequent drought events are one of the challenges faced worldwide in the context of climate change. There are multiple anecdotal evidence of dug wells and small streams running dry during  drought events in years 2015 and 2018 in Latvia. However, no comprehensive research has been made to assess groundwater drought and its ecological and socioeconomic impacts in Latvia and wider Baltic region. More intensive irrigation can further exaggerate the groundwater drought problem in the future. 

We aim to analyse past drought events from meteorological and groundwater drought perspective. Groundwater drought development and propagation is complex, however, we try to find the best simple predictors that can be used for evaluating purposes. We examine groundwater level data set from “Dricani” monitoring station with 14 groundwater wells uncovering unconfined heterogenous quaternary aquifer with well depths ranging from 2.5 to 15 m and monthly data records starting from 1970.-ies. Such a high number of wells in a single monitoring station permit detailed groundwater level analysis with a focus on local scale disturbances and groundwater drought propagation that could be caused by heterogeneous sediments in the aquifer, terrain and other drivers. 

We us “Dricani” groundwater level data series to calculate Standardized groundwater level index (SGI) (Bloomfield, Marchant 2013) revealing several major groundwater drought events during the last 50 years. Although largest groundwater drought events shows similar pattern within all the wells, minor changes in SGI can be identified that can be attributed to different depths of groundwater wells. 

The study is supported by fundamental and applied science research programme, project No. lzp-2019/1-0165 “Spatial and temporal prediction of groundwater drought with mixed models for multilayer sedimentary basin under climate change”.

References

Bloomfield JP, Marchant BP. 2013. Analysis of groundwater drought building on the standardised precipitation index approach. Hydrology and Earth System Sciences 17 (12): 4769–4787 DOI: 10.5194/hess-17-4769-2013
Analysing Conceptual Climate Models with Monte Carlo Basin Bifurcation Analysis
Authors: Gelbrecht Maximilian , Kurths Jürgen , Hellmann Frank
Published: March 2020

Many high-dimensional complex systems such as climate models exhibit an enormously complex landscape of possible asymptotic state. On most occasions these are challenging to analyse with traditional bifurcation analysis methods. Often, one is also more broadly interested in classes of asymptotic states. Here, we present a novel numerical approach prepared for analysing such high-dimensional multistable complex systems: Monte Carlo Basin Bifurcation Analysis (MCBB).  Based on random sampling and clustering methods, we identify the type of dynamic regimes with the largest basins of attraction and track how the volume of these basins change with the system parameters. In order to due this suitable, easy to compute, statistics of trajectories with randomly generated initial conditions and parameters are clustered by an algorithm such as DBSCAN. Due to the modular and flexible nature of the method, it has a wide range of possible applications. While initially oscillator networks were one of the main applications of this methods, here we present an analysis of a simple conceptual climate model setup up by coupling an energy balance model to the Lorenz96 system. The method is available to use as a package for the Julia language. 