bluuebunny/crossref_metadata_2025 huggingface dataset:
An up-to-date Mapping for the Movement and the Deformation of the Sinai Micro-plate from a Combined GPS Velocity Field
Authors: Saleh Mohamed , Masson Frederic , Abou-Aly Nadia , Mohamed Abdel-Monem
Published: March 2020

We use combined GPS velocities covering Sinai peninsula to estimate the current rates across the Sinai micro-plate boundaries. New GPS velocities were estimated for 67 sites located within and around Sinai (Arabia, Eurasia and Nubia plates) covering the time span 1999-2018 using GAMIT/GLOBK 10.6 (Herring et al., 2015). We have combined our velocity field with two other recent solutions of GPS sites located around Sinai area. We used the VELROT tool from GAMIT/GLOBK package to combine all solutions resulting in a velocity field of 265 GPS sites in ITRF2018. Then, we selected 61 sites that represent the Sinai plate interior to estimate the Euler pole of Sinai micro-plate. Our computed the Euler pole parameters, latitude, longitude, and angular velocity for Sinai are 53.3±1.8°, -7.8±2.2°, and 0.451±0.014°/Ma, respectively, which are comparable to previous estimates, but with better uncertainties. The relative block motions at the Sinai plate boundaries are estimated using the DEFNODE code (McCaffrey, 2002) by minimizing the GPS residual motions within the blocks in a least squares sense. Our block motion model for Sinai sub-plate shows a fault-parallel velocity at the Gulf of Aqaba of 4.7-4.5 mm/yr, associated with negligible fault-normal component, which decreased toward the north direction along the Dead Sea Transform Fault. On the other hand, an opening rate of 3 mm/yr is estimated at the southern part of the Gulf of Suez with negligible fault-parallel component. At central and northern parts of the Gulf of Suez, the opening rate decreases until it vanished at the northern part of the Suez Canal while the fault-parallel component increases.
Spatio-temporal patterns of crop signals: is UAV-based multispectral imagery a suitable tool to detect soil compaction at field scale?
Authors: Lindenstruth Frauke
Published: March 2020

Soil compaction due to heavy machinery is one of the major soil degradation threats in modern agriculture. Field traffic under unfavorable weather conditions can increase bulk density and penetration resistance, reduce soil hydraulic conductivity and plant growth. An increased surface runoff caused by a decreasing infiltration further grows the effects of nutrient leaching and the eutrophication of adjacent water bodies. For soil compaction prevention, it is necessary to know where soil compaction occurs. The detection of this issue is, however, cost, time and labor intensive.

The aim of this study is to evaluate the use of UAV-based multispectral imagery analyses to detect soil compaction pattern at field scale. Therefore, UAV imagery of two sugar beet (Beta vulgaris L.) fields were captured in April, June, July and November of 2019 to analyze different crop signals. The crop surface model and the NDVI were used as a predictor to reflect plant and biomass status. The k-means clustering algorithm was used to combine plant height and NDVI to detect spatial-temporal patterns of low crop performance. Sites with lower crop performance were assumed as potential sites of soil compaction; here, further measurements (penetration resistance, infiltration rate) were conducted and soil and yield samples were taken.

First results show that (1) spatio-temporal patterns of crop performance can be found; (2) sites with low crop performance have a lower infiltration rate and lower crop yield; (3) the measurements of penetration resistance are inconclusive.

As soil compaction reduces infiltration rate and yield, this study shows first indications that it is possible to detect soil compaction via plant signals using UAV. This has a big potential for practical use as costs for drones are declining and they are gaining popularity under farmers. Thus, the use of UAV may enable farmers to monitor their fields, identify areas of soil compaction and in the following implement measures against soil compaction.
Chemical Characterization of Particulate and Volatile Organic Compounds in the Rural Wintertime Atmosphere by CHARON PTR-ToF-MS
Authors: Wisthaler Armin , Müller Markus , Poulain Laurent , Piel Felix , Gräfe Ricarda , Spindler Gerald , Wiedensohler Alfred , Herrmann Hartmut
Published: March 2020

We have shown in previous work that Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) in combination with the “Chemical Analysis of Aerosol Online" (CHARON) inlet is a powerful tool for direct and online analysis of sub-µm particulate organic matter in the urban atmosphere. Herein, we report on the first CHARON PTR-ToF-MS measurements in the continental background environment, at the TROPOS Research Station in Melpitz near Leipzig (Germany) during a three week period in February 2019.

A state-of-the-art CHARON PTR-TOF 6000X2 instrument (IONICON Analytik GmbH, Austria) was used for measuring particulate organic compounds online (i.e., without filter pre-collection) and in real-time (< 1-min time resolution), at sub-ng m-3 mass concentrations, and on an elementary composition level. Periodic switching between the standard PTR-MS gas-phase inlet and the CHARON particle inlet made it possible to comprehensively measure atmospheric organic matter in both the gaseous and particulate state at a time resolution of 10 minutes. In addition, an aerosol mass spectrometer (HR-TOF-AMS) and an aerosol chemical speciation monitor (ACSM; both Aerodyne Inc., USA) were deployed for monitoring the composition of non-refractory particulate matter. A Dual Mobility Particle Size Spectrometer (TROPOS-type T-MPSS) was used for determining the total particle size distribution. In addition, particles were collected on filters once per day and analysed offline in the laboratory.

The CHARON PTR-TOF 6000X2 instrument operated stably and reliably over the three week measurement period. Our data show that a single instrument can be used for characterizing both gaseous and particle-bound organic matter in the atmosphere at 10 minute time resolution. The obtained data agree well with ACSM, HR-TOF-AMS and T-MPSS results. A comparison with the offline results obtained from the filter samples confirmed that the CHARON PTR-ToF-MS technique accurately measures the atmospheric concentrations of selected anhydrosugars and polycyclic aromatic hydrocarbons (PAHs). We also show that CHARON PTR-ToF-MS data are useful for improving the source apportionment of particles via positive matrix factorization (PMF).

This work is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654109 (ACTRIS-2). F. P. has received funding through the EU's Horizon 2020 programme under grant agreement Nº674911 (IMPACT). 
The TANGO mission: A satellite tandem to measure major sources of anthropogenic greenhouse gas emissions
Authors: Landgraf Jochen , Rusli Stephanie , Cooney Ryan , Veefkind Pepijn , Vemmix Tim , de Groot Zeger , Bell Andrew , Day James , Leemhuis Anton , Sierk Bernd
Published: March 2020

In this contribution, we present the Twin ANthropogenic Greenhouse Gas Observers (TANGO) mission, which is one of four candidate missions of ESA’s SCOUT program for the rapid prototyping and demonstration of observation techniques and science application using small-satellites. Over the period 2024-2027, TANGO will provide the unique opportunity for the global and independent monitoring of the major emission sources of the anthropogenic greenhouse gases CH4 and CO2. It will demonstrate a distributed monitoring system that can pave the way for future larger constellations of small-satellites allowing for enhanced coverage and temporal resolution. The TANGO mission consists of two agile small-satellites, each carrying one spectrometer flying in conjunction with the Copernicus Sentinel 5 mission. Regular joint TANGO and Sentinel 5 observations will be used to enhance the radiometric accuracy of the TANGO spectrometers. The first satellite measures spectral radiances in the shortwave infrared part of the solar spectrum (1.6 µm) to determine moderate to strong emissions of CH4 (≥ 10 Kt/yr) and CO2 (≥ 5 Mt/yr). The instrument has a field of view of 30 x 30 km2 at spatial resolutions small enough to monitor individual large industrial facilities (300 x 300 m2), with an accuracy to determine emissions on the basis of a single observation. Using the same strategy, the second satellite yields collocated NO2 observations from radiance measurements in the visible spectral range, supporting plume detection and exploiting the use of CO2/NO2 ratio observations to estimate CO2 emissions from offshore NO2 sources. TANGO will provide surface fluxes of specific emission types based on the combination of CH4, CO2 and NO2 observations at a high spatial resolution. In doing so, TANGO aims to uniquely complement the large current and planned Copernicus monitoring missions like Sentinel-5(P) and the CO2M High Priority Candidate Mission (HPCM) by providing unrivalled high-resolution monitoring of the major anthropogenic greenhouse gas emissions at a regular basis.
Climate elasticity of low-flows: the long-term impact of droughts
Authors: Andréassian Vazken , de Lavenne Alban
Published: March 2020

The long-term memory of catchments (carried by their hydrogeological characteristics) has a considerable impact on low-flow dynamics. Here, we present an exploratory study on a large French dataset to characterize the climate elasticity of low-flows and understand its long-term dependency. The climate elasticity of catchments is a simple concept (almost model-free) that allows analyzing the linear dependency of streamflow anomalies to climate anomalies (Andréassian et al., 2016). Widely-used for average annual streamflow, we propose to extend this concept to annual minimum monthly flow anomalies (QMNA) in order to characterize the climate dependency of QMNAs. By introducing progressively the linear dependency to the climatic anomalies of previous years, we further characterize the long-term memory of low-flows for the catchments of our set.

References

Andréassian, V., Coron, L., Lerat, J., and Le Moine, N. 2016. Climate elasticity of streamflow revisited – an elasticity index based on long-term hydrometeorological records, Hydrol. Earth Syst. Sci., 20, 4503-4524.

 
Forest above-ground biomass estimates across three decades from spaceborne scatterometer observations
Authors: Santoro Maurizio , Cartus Oliver , Carvalhais Nuno , Besnard Simon , Fan Naixin
Published: March 2020

The large uncertainty characterizing the terrestrial carbon (C) cycle is a consequence of the sparse and irregular observations on the ground. In terms of observations, spaceborne remote sensing has been achieving global, repeated coverages of the Earth since the late 1970s, with a continuous increase in terms of density of observations in time and spatial resolution, thus potentially qualifying as data source to fill such gap in knowledge. Above-ground biomass is a baseline for quantifying the terrestrial C pool; however, remote sensing observations do not measure the organic mass of vegetation. Above-ground biomass (AGB) of forests can only be inferred by inverting numerical models relating and combining multiple remote sensing observations. One of the longest time record of observations from space is represented by the backscattered intensity from the European Remote Sensing Wind Scatterometer (ERS WindScat) and the MetOp Advanced Scatterometer (ASCAT), both operating at C-band (wavelength of 6 cm). An almost unbroken time series of backscatter observations at 0.25° spatial resolution exists since 1991 and data continuity is guaranteed in the next decades. In spite of the weak sensitivity of C-band backscatter to AGB, wall-to-wall estimates of AGB have been derived from high-resolution SAR observations by exploiting multiple observations acquired in a relatively short time period  (Santoro et al., Rem. Sens. Env., 2011; Santoro et al., Rem. Sens. Env., 2015). We have now applied this approach to generate a global time series of AGB estimates for each year between 1992 and 2018 from the C-band scatterometer data at 0.25° spatial resolution. The spatial patterns of AGB match known patterns from in situ records and other remote sensing datasets. The uncertainty of our AGB estimates is between 30% and 40% of the estimated value at the pixel level, providing strong confidence in multi-decadal AGB trends. We identify a constant increase of biomass across most boreal and temperate forests of the northern hemisphere. In contrast, we detect severe loss of biomass throughout the wet tropics during the 1990s and the beginning of the 2000 decade in consequence of massive deforestation. This loss in biomass is followed by a steady increase during the 2000s and the beginning of the most recent decade, coming more recently into saturation. Overall, we find that the global AGB density at 0.25° steadily increased by 9% from 71.8 Mg ha-1 Pg in the 1990s to 78.1 Mg ha-1 in the 2010s. Combining our AGB density estimates with the annual maps of the Climate Change Initiative (CCI) Land Cover dataset, we show that total AGB in forests decreased slightly from 566 Pg in the 1990s to 560 Pg in the 2000s, then increased to 593 Pg in the 2010s, resulting in an almost 5% net increase during the last three decades.
Changes in future precipitation characteristics over the Alpine region in a multi-model convection-permitting ensemble: the role of shifting intensities
Authors: Sobolowski Stefan ,   CORDEX Flagship Pilot Study on Convection over Europe and the Mediterranean
Published: March 2020

Changes in precipitation at local to regional scales in a warmer world remain highly uncertain. This is especially true of both moderate and high extremes (e.g. > 90%-iles and > 99.9%-iles, respectively). While a relationship between increasing model resolution and increasing precipitation (both means and extremes) appears to be present for both GCMs and RCMs there are conflicting results when convection-permitting scales are reached. These differences can be region as well as model dependent. A project under the auspices of the World Climate Research Program’s (WCRP) Coordinated Regional Downscaling Experiments Flagship Pilot Studies program (CORDEX-FPS) was established to investigate these, and other issues. This initiative aims to build first-of-their-kind ensemble climate experiments using convection permitting models to investigate present and future convective processes and related extremes over Europe and the Mediterranean. In this presentation we offer a first look at the scenario simulations (Historical 2000-2009 and RCP8.5 2090-99 timeslices) and an analysis of precipitation changes and their drivers over various sub-regions of a large domain, which cover the Alps, parts of central Europe and the Mediterranean and Adriatic coasts (0-17E x 40-50N). This study employs an innovative precipitation separation algorithm specifically designed for use with km-scale models. The algorithm separates convective, stratiform and orographic precipitation, which allows for a more nuanced understanding of projected change. The method is based on physical processes such as vorticity and vertical velocity. This new approach focuses on the physical processes leading to precipitation of a certain types rather than use the circular reasoning of employing the result to determine the cause. As a result we are able to see that despite overall drying in some seasons increasing intensity of convective precipitation contributes toward the shift to more intense extremes. We conclude with a discussion of the changes to the underlying physical processes driving convective and other types of precipitation at highly localized scales.
Hybridization capture of larch (Larix Mill.) chloroplast genomes from sedimentary ancient DNA reveals past changes of Siberian forest
Authors: Schulte Luise , Bernhardt Nadine , Stoof-Leichsenring Kathleen , Zimmermann Heike , Pestryakova Luidmila , Epp Laura , Herzschuh Ulrike
Published: March 2020

Siberian larch (Larix Mill.) forests dominate vast areas of northern Russia and contribute important ecosystem services to the earth. To be able to predict future responses of these forests to a changing climate, it is important to understand also past dynamics of larch populations. One well-preserved archive to study vegetation changes of the past is sedimentary ancient DNA (sedaDNA) extracted from lake sediment cores. We studied a lake sediment core covering 6700 calibrated years BP, from the Taymyr region in northern Siberia. To enrich the sedaDNA for DNA of our focal species Larix, we combine shotgun sequencing and hybridization capture with long-range PCR-generated baits covering the complete Larix chloroplast genome. In comparison to shotgun sequencing, hybridization capture results in an increase of taxonomically classified reads by several orders of magnitude and the recovery of near-complete chloroplast genomes of Larix. Variation in the chloroplast reads confirm an invasion of Larix gmelinii into the range of Larix sibirica before 6700 years ago. In this time span, both species can be detected at the site, although larch populations have decreased from a forested area to a single-tree tundra at present. This study demonstrates for the first time that hybridization capture applied to ancient DNA from lake sediments can provide genome-scale information and is a viable tool for studying past changes of a specific taxon.
Analysis of energy conversion processes at kinetic scales associated with a series of dipolarization fronts observed by MMS during a substorm
Authors: Alqeeq Soboh , Le Contel Olivier , Canu Patrick , Retino Alessandro , Chust Thomas , Mirioni Laurent ,   MMS team
Published: March 2020

In July 2017, the MMS constellation was in the magnetotail with an apogee of 25 Earth radii
and an average inter-satellite distance of 10 km (i.e. at electron scales). On 23 July around
16:19 UT, MMS was located at the edge of the current sheet which was in a quasi-static
state. Then, MMS suddenly entered in the central plasma sheet and detected the local onset
of a small substorm as indicated by the AE index (~400 nT). Fast earthward plasma flows
were measured for about 1 hour starting with a period of quasi-steady flow and followed by
a saw-tooth like series of fast flows associated with dipolarization fronts. This plasma
transport sequence finished with a flow reversal still occurring close to the magnetic
equator. In the present study, we investigate the energy conversion processes at ion and
electron scales for these different phases with particular attention on the processes in the
vicinity of the dipolarization fronts.
A-posteriori Analyses of Pattern Recognition Results
Authors: Langer Horst , Falsaperla Susanna , Hammer Conny
Published: March 2020

Data-driven approaches applied to to large and complex data sets are intriguing, however the results must be revised with a critical attitude. For example, a diagnostic tool may provide hints for a serious disease, or for anomalous conditions potentially indicating an impending natural risk. The demand of a high score of identified anomalies – true positives -  comes together with the request of a low percentage of false positives. Indeed, a high rate of false positives  can ruin the diagnostics. Receiver Operation Curves (ROC) allows us to find a reasonable compromise between the need of accuracy of the diagnostics and robustness with respect to false alerts.

In multiclass problems success is commonly measured as the score for which calculated and target classification of patterns matches at best. A high score does not automatically mean that a method is truly effective. Its value becomes questionable, when a random guess leads to a high score as well. The so called “Kappa Statistics” is an elegant way to assess the quality of a classification scheme. We present some case studies demonstrating how such a-posteriori analysis helps corroborate the results.

Sometimes  an approach does not lead to the desired success. In thes cases, a sound a-posteriori analysis of the reasons for the failure often provide interesting insights into the problem, Those problems may reside in an inappropriate definition of the targets, inadequate features, etc. Often the problems can be fixed just by adjusting some choices. Finally,  a change of strategy may be necessary in order to achieve a more satisfying result. In the applications presented here, we highlight the pitfalls arising in particular from ill-defined targets and unsuitable feature selections.

The validation of unsupervised learning is still a matter of debate. Some formal criteria (e. g. Davies Bouldin Index, Silhouette Index or other) are available for centroid-based clustering where a unique metric valid for all clusters can be defined. Difficulties arise when metrics are defined individually for each single cluster (for instance, Gaussian Model clusters, adaptive criteria) as well as using schemes where centroids are essentially meaningless. This is the case in density based clustering. In all these cases, users are better off when asking themselves whether a clustering is meaningful for the problem in physical terms. In our presentation we discuss the problem of choosing a suitable number of clusters in cases in which formal criteria are not applicable. We demonstrate how the identification of groups of patterns helps the identification of elements which have a clear physical meaning, even when strict rules for assessing the clustering are not available.    

 

 
The October 1940 extreme flood in the Pyrenees revisited: validation of some hypotheses based on hydraulic simulations
Authors: Gaume Eric , Charpentier-Noyer Maryse , Payrastre Olivier
Published: March 2020

One of the most impressive flash floods of the last century in France, as in Spain, occurred in the Eastern part of the Pyrenees on the 17th and 18th of October 1940. 47 people died in France during this extraordinary event and more than 100 in Catalunia. This flood caused considerable damages to buildings and, in particular, destroyed the center of the thermal town of Vernet-les-Bains on the slopes of the mount Canigou. The maximum observed 24-hour rainfall amount was close to one meter and remains until now one of the French record values. This flooding has already been widely documented both by the state technical services and by scientists of the time. Much of this documentation, which has been archived and is still available, makes it possible to propose new evaluations in the light of the recent advancements in flash floods studies. The conclusions of this work of flood reanalysis are presented, and are supplemented here by hydraulic simulations in order to test different hypotheses concerning the timing and magnitude (i.e. discharge values) of the flood. The Basilisk software (finite volume method for shallow water equations with adaptive mesh refinement) is used to conduct the 2D-hydraulic simulations. The initial reanalysis of the flood revealed that (1) the peak discharge values estimated in 1940, on which local risk assessment studies are based, had probably been largely over-estimated; (2) a sudden increase of local water levels, described by eye-witnesses in the town of Elne, was due to the breach of a railway embankment in the floodplain upstream the town. The hydraulic simulations, carried out both with the peak discharge estimated in 1940 and with the re-evaluated one, show that the former values are not compatible with the flood witnesses’ accounts - which retrace the chronology of the episode - or with the surveyed water levels. The revised and reduced peak discharge appears to be more realistic according to the data retracing the event. Moreover, the presence of the breach in the railway line embankment appears to explain the maximum water levels observed in the town of Elne. This work illustrates that major past-flood events may be re-interpreted at the light of our increased scientific knowledge provided that they have been well documented at the time of their occurrence, which is often the case for major devastating floods.
Assessing geo-hydrological hazards with Remote sensing data in Antananarivo (Madagascar) historical center
Authors: Ciampalini Andrea , Frodella William , Spizzichino Daniele , Margottini Claudio , Casagli Nicola
Published: March 2020

Landslides represent a major threat in Madagascar, especially in the central and eastern regions during the rainy season (from November thru May), when heavy rains from tropical storms and cyclones saturate the soil making mountains and hillsides more susceptible to slope instability phenomena. The capital Antananarivo has been particularly affected by geo-hydrological risks in the last years, with special regards to the March 2015 event, when cyclones triggered diffuse flooding and landslides causing damages, casualties and over 20000 evacuees. Antananarivo area is characterized by the most important historical and cultural heritages in Madagascar, such as the ancient fortifications and palaces at Ambohimanga (located just 20 km north of the town area), protected as an UNESCO World Heritage site since 2001, and the Rova of Antananarivo royal palace complex. Antananarivo was called Analamanga (the "blue forest"), until 1610, when the merina King Andrianjaka built his palace on the highest hill of the city, and built the first Rova (meaning “fort” in Malagasy) to post a garrison of 1000 man. Antananarivo developed from the site of the first Rova at the top of Analamanga hill at about 1480 m a.s.l., becoming the current historical core (the Upper town or the “Haute Ville”), gradually spreading over the whole Analamanga hill slopes (Middle town or the “Ville Moyen”).

In October 2017, a geo-hydrological hazard mapping was performed in the Upper Town by combining field surveys, remote sensing and geomatic data analysis. The output of the performed activities consisted in the creation of a detailed geodatabase, which by means of geomatics methods was integrated with field data, topographic data, high resolution digital terrain models (2 and 1 m spatial resolution), very high resolution optical satellite images (Pleiades-1A with 0.5 m resolution) and homogenized in a Geographic Information System (GIS). This geodatabase represents a fundamental tool for susceptibility, hazard and risk assessment/management activities to be performed in the Antananarivo hill area for a proper management of its cultural and historical heritages.
Links between remagnetizations and superchrons. New experiments and new results.
Authors: Villalaín Juan José , Calvín Pablo , Bógalo María Felicidad , Falcón Irene , Casas-Sainz Antonio M.
Published: March 2020

Chemical widespread remagnetizations are especially frequents during superchrons. An interesting issue is whether this relationship is due to especial requirements of the mechanism of acquisition of the remagnetizations and their timing. One example of this type of remagnetizations during a superchron is the one recorded by the Jurassic carbonates from the Central High Atlas (CHA) in Morocco. This normal polarity overprint has been dated ca 100 Ma, comparing the remagnetization direction with the African APWP, i.e. during the Cretaceous Normal Superchron (CNS) and also during the extensional stage of these inverted basins.

After several paleomagnetic studies performed in this area in the framework of a big research project, paleomagnetic and rock magnetic data from a set of more than 600 paleomagnetic sites distributed over an area of 10000 km2 are available. The CHA cretaceous remagnetization has been observed in all these sites with the same magnetic properties: a viscous paleomagnetic component with maximum unblocking temperatures of 200-250ºC and the remagnetization normal polarity component up to 450–500ºC. Both are carried by authigenic uniaxial SSD magnetite. The paleomagnetic direction calculated by small circle intersection method (SCI) is also similar in the different locations of this wide area.

The mechanism proposed for this type of widespread remagnetization is the generation of magnetite grains due to the heating related with burial. The homogeneous direction of the remagnetization seems to suggest an acquisition for a short event at 100 Ma. However, the extensional stage of these basins lasts tens of millions years keeping the necessary burial conditions for growth of magnetite grains covering several polarity chrons including the CNS.

In this work we address the question of timing under with these processes happened, i.e. short vs. long remagnetization periods. We propose the hypothesis that the ca. 100 Ma paleomagnetic direction shows by the remagnetization is just the average of magnetic moments of the entire SSD magnetite population that grow from the Middle Jurassic up to the Cenozoic. Grains block the magnetic moments when they grow above their critical volume, keeping the magnetic polarity generating over time a distribution of grains in normal and reverse polarity groups. To test this hypothesis we develop 1) simulations for the calculation of magnetization directions assuming a homogeneous and constant growth of magnetite crystals and 2) rock magnetic experiments to demonstrate the presence of SSD magnetite grains with opposed magnetic moments. These experiments intend to assess the effectiveness of the SSD grains carrying the remagnetization by comparing the NRM and the ARM signal through the pseudo-Thellier approach.
PBL climatology using IGRA radiosounding data in Mediterranean Basin
Authors: Summa Donato , Madonna Fabio , Tramutola Emanuele , Marra Fabrizio , De Rosa Benedetto , Di Girolamo Paolo
Published: March 2020

The planetary boundary layer height (PBL) is a critical variable in many applications such as NWP, air quality and climate models. The study of the PBL involves several process and parameters: exchange of momentum, heat, water vapour and tracers from the surface to the free atmosphere therefore,  PBL representation in numerical  models is difficult to achieve and observation are used to improve the quality of the implemented parameterizations.

This presentation will illustrate a climatology of the height of the PBL and its trend since 1978 to present at different in the Mediterranean Basin.

The height of the PBL is calculated using the maximum vertical gradient of potential temperature  (θ) obtained from radio Station belonging to the IGRA (Integrated Global Radiosonde) archive related in the Europe Region) and to GRUAN network (GCOS Reference Upper Air Network).  

The IGRA consists of quality-controlled radiosonde observations of temperature, humidity, and wind at stations across all continents. The earliest year of data is 1905, and the data are updated on a daily basis. Record length, vertical extent and resolution, and availability of variables varies among stations and over time. The GRUAN is an international reference observing network of sites measuring essential climate variables above Earth's surface, designed to fill an important gap in the current global observing system. GRUAN measurements are providing long-term, high-quality climate data records from the surface, through the troposphere, and into the stratosphere. 

An estimate of uncertainty will be also discussed and correlated with the recent climate changes at the global scale and in the Mediterranean Basin.
A Strainmeter Array Along the Alto Tiberina Fault System, Central Italy
Authors: Chiaraluce Lauro , Bennett Rick , Mencin David , Barchi Massimiliano , Bohnhoff Marco
Published: March 2020

The Alto Tiberina fault (ATF) in the Northern Apennines (Central Italy) is a low-angle normal fault (mean dip 20°) that is the target of TABOO (The Alto Tiberina Near Fault Observatory), a state-of-art research and monitoring infrastructure based on multidisciplinary sensors. With the STAR’s project, we intend to deploy a strain- and seismo-meter array in six shallow boreholes to complement and enhance TABOO. This will happen with the active contribution of US National Science Foundation and International Continental Scientific Drilling Program (ICDP Project ID: ICDP-2018/05).

Existing seismic data from TABOO reveal microseismicity, at a consistently high rate on the ATF fault plane, including repeating earthquakes (RE). REs together with a steep gradient in crustal velocities measured by GPS and transient surface motion lasting for few months and coinciding with seismic swarms, support the hypothesis that portions of the ATF are creeping aseismically.

Recent studies document that any given patch of a fault can creep, nucleate slow earthquakes, and also host large earthquakes. Thus, these observations are forcing a revolution in our way of thinking about how faults accommodate slip. However, the interaction between creep, slow, and regular earthquakes is still poorly documented by observation. The ATF fault is perhaps the best place in the world to understand at local scale the mechanisms and implications of stress transfer process between seismic and aseismic fault segments. With STAR we will collect the Open Access data to illuminate the physics that allows for both seismic and aseismic slip on a single fault patch, with potentially transformational implications for seismic hazard and risk assessment globally.

STAR will consist of six 80-160m deep vertical boreholes covering the portion of the ATF that exhibits REs at shallow depth (~4 km), identified with waveforms analysis. The observatory will provide the international community an opportunity to study creep at local scale and over periods of minutes to months poorly constrained by other geophysical instruments. We will also deploy downhole seismometers and pressure transducers co-located with the strainmeters, and each station will be equipped with surface GPS and a meteorological instrument. The suite of instruments will enable the collection and calibration of strain records with exquisitely high precision, allowing for a quantitative characterization of ATF creep (~1mm over <1km2), enhanced monitoring of microseismicity (below Mc 0.5), and allowing correlation between degassing (CO2, Rn) measurements and subsurface strain.
Modeled based analysis of fish farm emissions impact on the fjord biogeochemistry
Authors: Yakushev Evgeniy , Berezina Anfisa
Published: March 2020

To investigate the impacts of fish farm emissions, we coupled the biogeochemical C-N-P-Si-O-S-Mn-Fe transformation model BROM with a 2-Dimensional Benthic-Pelagic transport model (2DBP), considering vertical and horizontal transport in the water and upper 5 cm  sediments along a 10000 m transect centered on a fish farm. The 2DBP model had 25 m horizontal resolution and was forced by hydrophysical model data for the Hardangerfjord in western Norway. The model predicted significant impacts on seafloor biogeochemistry up to 500 meters from the fish farm (e.g., increased organic matter in sediments, oxygen depletion in water and sediments, denitrification, metal and sulfur reduction) as well as detectable decreases in oxygen and increases in ammonia, phosphate and organic matter in the water near to the fish farm cages. The model results are compared with field data from the Hardangerfjord in August 2016 and indicated satisfactory model performance.
Surface flux errors in asynchronous coupling of GCM
Authors: Perrot Xavier , Duvel Jean-Philippe , Guez Lionel
Published: March 2020

In coupled general circulation model, the accuracy of momentum and energy exchange at the air-sea interface is still a potential source of significant bias. In the framework of the COCOA project we investigate new methods (both mathematical and numerical) to have a more correct flux representation. One important source of error is the asynchronous coupling between oceanic and atmospheric model. Indeed, the time step of the coupling is generally longer than time steps used by either the atmospheric or the oceanic model. This introduces inconsistencies between the free evolution of the two models due to the exchange parameters that are held constant since the last coupling time step. In particular, non-synchronous exchange coefficients may lead to error in the diurnal evolution of the coupled system, or to bias in the ocean mixed layer temperature for period where surface fluxes increases or decrease linearly.

In order to evaluate the potential amplitude of this error, and its regional and sea- sonal distribution, we use the hourly fluxes that are available in the new ECMWF ERA5 re-analyses. The error due to asynchronous coupling is first evaluated by inspecting the flux difference between two successive time-steps. Results show more important differences over the western boundary currents and the circumpolar current for all the fluxes except for the solar flux. We also observe larger differences in summer compared to winter in the respective hemisphere. By taking in account the geometrical variation of the solar flux we show how we can reduce the error for the solar flux.

In a second time we are calculating the statistics for the linear increase and decrease of the flux for a fixed period (ig one day, two days...) over all the ocean for all the fluxes except the solar one. The results are showing coefficients that are decreasing as the period increase. We also use those coefficient in a simple mixed layer model to calculate the error made over the period of calcul. On the contrary we see the appearance of a plateau at two-three days on the impact of this linear bias. Finally, using the De Boyer de Montaigu climatology for the mixed layer height we show that the linear bias could lead to temperature change up to 0.1K.
Toward a UK fire danger rating system: Understanding fuels, fire behaviour, and impacts
Authors: Clay Gareth , Belcher Claire , Doerr Stefan , Elliott Andy , Hardiman Mark , Kettridge Nick , Millin-Chalabi Gail , Morison James , Santin Cristina , Smith Thomas
Published: March 2020

Wildfires in temperate regions like the UK can cause major impacts for ecosystems, society and human health and wellbeing. Under changing climate and land use patterns it is therefore important to better understand how we can assess the danger posed by fires in the landscape. Major wildfire events in the UK over recent years have highlighted the risk posed by wildfires, and has led to recognition of wildfire as an environmental hazard in the UK National Risk Register.

Fire Danger Rating Systems (FDRS) are designed to assess the fuel and weather to provide estimates of flammability and likely fire behaviour under those conditions. These danger ratings can inform management decisions for land managers, direct resourcing plans for FRS teams, and feed into strategic planning for local and national governments. However, the UK does not yet have a fit-for-purpose FDRS and we lack the fundamental scientific and end-user understanding to predict effectively the likelihood, behaviour and impact of wildfire incidents in the UK at present and under future climate and land use scenarios.

This poster will present the outline and structure of a new NERC-funded, multi-institution, 4-year project that will develop the underpinning knowledge and tools to develop a UK FDRS. We are very keen to hear from the wildfire community about ways in which this work could help you with your activities and to link up with other projects.
Aesthetical issues with stochastic evaluation.
Authors: Sargentis George-Fivos , Ioannidis Romanos , Meletopoulos Ilias Taygetos , Dimitriadis Panagiotis , Koutsoyiannis Demetris
Published: March 2020

This research uses a stochastic computational tool (2D-C) for characterizing images in order to examine similarities and differences among artworks. 2D-C is measures the degree of variability (change in variability vs. scale) in images using stochastic analysis.

Apparently, beauty is not easy to quantify, even with stochastic measures. The meaning of beauty is linked to the evolution of human civilization and the analysis of the connection between the observer and the beauty (art, nature) has always been of high interest in both philosophy and science. Even though this analysis has mostly been considered part of the so-called social studies and humanities, mathematicians have also been involved. Mathematicians are generally not specialized to contribute, through their expertise, in sociopolitical analysis of messages and motivations of art but have been consistently applying mathematical knowledge, which is their expertise, in trying to explain aesthetics. In most of these analyses, the question at hand is if what is pleasing to the eye or not can be explained though mathematics.

Historically, it is known that from the time of the ancient Egyptian civilization a mathematic rule of the analogies of human body as models of beauty had been developed, and later in ancient Greece, the mathematicians Pythagoras and Euclid were the first known to have searched for a common rule (canon) existing in shapes that are perceived as beautiful. Euclid's Elements (c. 300 BC), for example, contains the first known definition of the “golden ratio”.

The opinions of later philosophers on this pursuit of mathematicians in the analysis of aesthetics were more varied. Leibniz, for example, believed that there is a norm behind every aesthetic feeling which we simply don’t know how to measure. On the contrary, Descartes supports that instead of regarding the aesthetic quality as an inherent quality of a physical object, the distinction of mind and nature have allowed humans to incorporate their own subjective feelings in determining their aesthetic preferences.

Thus many artists knew and apply math and geometry in their artwork, many philosophers tried to connect math and arts. Hence, it might be interesting to examine art work through a stochastic view. Stochastic analyses of the examined artworks are presented using climacograms and through stochastic evaluation with 2D-C we try to quantify some aspects of the artists’ expression. 
Ice thickness measurements of the debris covered Ngozumpa glacier, Nepal
Authors: Nicholson Lindsey , Maussion Fabien , Mayer Christoph , Pritchard Hamish , Lambrecht Astrid , Wirbel Anna , Klug Christoph
Published: March 2020

The presence of extensive debris cover on glaciers in parts of High Mountain Asia increases the certainty about the present day amount of ice, its ongoing rate of change and resultant impact on global sea level rise, regional water and local hazards

Here we use ground penetrating radar measurements of ice thickness for the Ngozumpa glacier, a large debris-covered glacier in Nepal, to explore the challenges of using such data to calculate glacier volume, and to compare how these field measurements compare to the modelled glacier thickness for this glacier generated by the four models used in the global consensus glacier ice thickness dataset, which suggested the region holds 27% less ice than previous estimates (Farinotti and others, 2019). We also compare the ice thickness measured at Ngozumpa glacier to existing data from the smaller neighboring Khumbu glacier and evaluate the maximum volume of a possible moraine dammed lake at this site.
Ice front blocking of ocean heat transport to an Antarctic ice shelf
Authors: Wåhlin Anna , Steiger Nadine , Darelius Elin , Assmann Karen , Glessmer Mirjam , Ha Ho Kyung , Herraiz-Borreguero Laura , Heuzé Celine , Jenkins Adrian , Kim Tae Wan , Mazur Aleksandra , Sommeria Joel , Viboud Samuel
Published: March 2020

Shoreward oceanic heat flux in deep channels on the continental shelf typically far exceeds that required to match observed ice shelf melt rates, suggesting other critical controls.  IN the present study we study the depth-independent (barotropic) and the density-driven (baroclinic) components of the flow of warm ocean water towards an ice shelf. Using observations from the Getz Ice Shelf system as well as geophysical laboratory experiments on a rotating platform, it is shown that the dramatic step shape of the ice front blocks the barotropic component, and that only the baroclinic component, typically much smaller, can enter the sub-ice cavity.  A similar blocking of the barotropic component may occur in other areas with comparable ice-bathymetry configurations, which may explain why changes in the density structure of the water column have been found to be a better indicator of basal melt rate variability than the heat transported onto the continental shelf. Representing the step topography of the ice front accurately in models is thus important for simulating the ocean heat fluxes and induced melt rates.
Forecast based action: developing triggers for preventing food insecurity in Eastern Africa
Authors: van den Homberg Marc , Guimarães Nobre Gabriela , Bolton Edward
Published: March 2020

The project “Forecast based Financing for Food Security” (F4S) was initiated in July 2019 with the aim to provide a deeper understanding of how forecast information could be routinely used as a basis for financing early action for preventing food insecurity in pilot areas in Ethiopia, Kenya, and Uganda. The F4S project is linked to the existing Innovative Approaches in Response Preparedness Project and is in response to the growing interest and attention placed in recent years by academic institutions, development and humanitarian agencies on creating evidence that can leverage risk prevention and disaster risk reduction.

To ensure adequate forecast-based actions one needs to have the right information and evidence to guide fast decision-making. Key enabling aspects are an understanding of the impact of food insecurity, the resources needed to address it and an insight in the associated costs, beneficiaries’ preferences and lead times. In response to that, the F4S is currently:

Developing an impact-based probabilistic food insecurity forecasting model using Machine Learning algorithms and datasets of food insecurity drivers;

Collecting local evidence on food insecurity triggers and information on individual preferences on key design elements of cash transfer mechanisms through surveys and choice experiments;

Evaluating the cost-effectiveness of different cash transfer mechanisms.

This PICO presentation seeks to share lessons learnt and preliminary results on the development of triggers for enabling early action against the first signs of food insecurity in Eastern Africa. It presents key results obtained through surveys and choice experiments regarding local knowledge in association with food insecurity and aid design. Furthermore, it presents the potential cost-effectiveness and advantages of acting based on forecasts.