bluuebunny/crossref_metadata_2025 huggingface dataset:
A global compilation of known-origin keratin hydrogen and oxygen isotope data for wildlife and forensic research
Authors: Magozzi Sarah , Contina Andrea , Wunder Michael , Vander Zanden Hannah , Bowen Gabriel
Published: March 2020

Variations in stable hydrogen (δ2H) and oxygen (δ18O) isotope ratios have been used in wildlife and forensic applications to infer the provenance of biological tissues by comparing isotopic measurements for unknown samples to geographically indexed measurements or predictions. Tissues composed of the structural protein keratin have been targeted in many systems, leading to a legacy of published data for known-origin samples. An open synthesis of these data would be useful to support broader analysis of keratin isotope patterns across biological systems and as a reference data collection for future studies.

Significant differences in sample preparation and analysis protocols and calibration and normalization approaches among laboratories have created substantial challenges in the integration of these data, however. Here we identify and assess factors that might be limiting comparability of δ2H and δ18O data among laboratories. These include sample type and sampling method, procedure for lipid extraction, whether and how partial exchange of keratin H with atmospheric moisture has been addressed, which laboratory reference materials have been used, drying and handling protocols, analysis method, and quality of chromatography for O isotopic analyses. We compile a list of reference materials (including Utah, USGS, and Saskatoon standards) and their established values, and develop a set of ‘rules’ and corrections to account for differences in processing methods and standards as well as the associated uncertainty. We apply these corrections to more than 2500 known-origin data from the literature and demonstrate that the comparability of isotopic data among laboratories is greatly improved by linking all measurements to the same scales. We highlight both the potential of the harmonized dataset for use in wildlife and forensic research as well as substantial challenges and limitations that remain.
Future circulation changes over the EURO-CORDEX domain
Authors: Ozturk Tugba , Matte Dominic , Christensen Jens Hesselbjerg
Published: March 2020

The occurrence of extreme weather events and climate extremes over Europe and the Mediterranean region are believed to be associated with changes and variability in the mid-latitude atmospheric circulation. CMIP5 models exhibits a substantial decrease in mid-latitude mean storm track activity for summer under climate change for a variety of scenarios. In this work, we aim to investigate future change in summer circulation and its implication for summer temperature and precipitation extremes over Europe particularly focusing on the Southeastern Mediterranean. EURO-CORDEX regional climate projections at 0.11° grid-mesh are used to analyze future climate projections addressing climate warming targets of 1°C, 2°C and 3°C, respectively. Simple scaling with the global mean temperature change is applied to the regional climate projections for the variables in concern in order to provide robust signals not to be dependent on climate sensitivity. Our focus in this study is on monthly mean geopotential height, winds at mid- and lower-troposphere as indicators of the simulated circulation changes.
Ice avalanche risk management from the Planpincieux glacier (Courmayeur - Italy)
Authors: Perret Paolo , Troilo Fabrizio , Gottardelli Simone , Mondardini Luca , Dematteis Niccolò , Giordan Daniele , Segor Valerio
Published: March 2020

Instabilities occurring on temperate glaciers in the Alps have been the subject of several studies, which have highlighted preliminary conditions and possible precursory signs of break-off events.

Since 2013, the Planpincieux Glacier, located on the Italian side of Mont Blanc massif (Aosta Valley), has been studied to analyse the dynamics of ice collapses in a temperate glacier.

These analyses have been conducted for several years, enabling the assessment of surface kinematics on the lower glacier portion and the different instability processes at the glacier terminus. During the period of the study, especially in the summer seasons, increases in velocities of the whole right side of the glacier tongue have been recorded. This fast sliding movement is mainly induced by water flow at the bottom of the glacier.

In 2019 summer season, the increase of speed coincided with the opening of a large crevasse, which outlined a fast moving ice volume, assessed by photogrammetric techniques as 250.000 m3.

According to the risk scenarios, the collapse of this ice volume from the glacial body would have reached the valley floor, potentially affecting the access road to the Val Ferret valley.

Considering the potential risk, a civil protection plan has been deployed by the monitoring team of the Aosta Valley Autonomous Region, Fondazione Montagna sicura and CNR-IRPI.

Glacier displacements, variations in the glacier morphology and environmental variables, such as air temperature, rain and snowfall, have all been taken into account to implement the monitoring plan.

This work outlines and summarises the steps used to develop the scientific knowledge into an integrated monitoring plan and a closure plan for the Val Ferret valley.
Spatial interpolation of daily precipitation using random forest
Authors: Sekulic Aleksandar , Kilibarda Milan , Heuvelink Gerard B.M. , Nikolić Mladen , Bajat Branislav
Published: March 2020

Regression kriging is one of the most popular spatial interpolation techniques. Its main strength is that it exploits both spatial autocorrelation as well as information contained in environmental covariates. While regression kriging is still dominant, in the past few years machine learning, especially random forest, is increasingly being used for mapping. Machine learning is more flexible than multiple linear regression and can thus make better use of environmental covariates. But machine learning typically ignores spatial autocorrelation. Several attempts have been made to include spatial autocorrelation in random forest, by adding distances to observation locations and other geometries to the set of covariates. But none of these studies have tried the obvious solution to include the nearest observations themselves and the distances to the nearest observations as covariates. In this study we tried this solution by introducing and testing Random Forest for Spatial Interpolation (RFSI). RFSI trains a random forest model on environmental covariates as well as nearest observations and their distances from the prediction point. We applied and evaluated RFSI for mapping daily precipitation in Catalonia for the 2016-2018 period. We trained four models (random forests, RFsp, pooled regression kriging and RFSI) using 63,927 daily precipitation observations from 87 GHCN-stations located in Catalonia. Maximum and minimum daily temperatures and IMERG precipitation estimates (derived from the GPM mission) were used as environmental covariates for all four models. Results based on 5-fold cross validation showed that RFSI (R-square 69.4%, RMSE 3.8 mm) significantly outperformed all random forest (R-square 50.6%, RMSE 3.8 mm), RFsp (R-square 55.5%, RMSE 4.6 mm) and pooled regression kriging (R-square 65.3%, RMSE 4.0 mm). Finetuning RFSI could potentially improve prediction accuracy even more. In addition to improved prediction accuracy, RFSI has the advantage that it uses much fewer spatial covariates than RFsp.
Effects of the solar wind dynamic pressure on the accelerated cometary ions in the magnetosphere of comet 67P
Authors: Timar Aniko , Nemeth Zoltan , Szego Karoly , Dósa Melinda , Nagy Balazs
Published: March 2020

Rosetta observed medium-energy ions around comet 67P/Churyumov-Gerasimenko while orbiting deep inside the coma. These ions are thought to be accelerated towards the anti-sunward direction by some acceleration mechanism in the outer regions of the cometary magnetosphere. They usually reach energies up to 100-1000 eV and undergo deceleration in the dense neutral coma surrounding the nucleus. These ions usually appear in the ion dynamic spectrum as a new population rising from the low energy background, their energy peaking around 1000 eV and then decreasing until the population disappears again. We investigated the properties of these ions, as well as the relationship between the solar wind pressure and the energy of the medium-energy ions to discover the cause of the observed time variation. We show that there is a correlation between the solar wind dynamic pressure around the comet and the energy of the accelerated ions.
A Real-time Ensemble Hydrological Forecasting System over Germany at Sub-seasonal to Seasonal Time Range
Authors: Najafi Husain , Thober Stephan , Boeing Friedrich , Rakovec Oldrich , Kelbling Matthias , Müller Sebastian , Marx Andreas , Samaniego Luis
Published: March 2020

Real-time hydrological forecasting provides valuable information to mitigate the impact of extreme hydrological events such as flood and drought. An ensemble hydrological forecasting system is developed to investigate the hydrological predictability at sub-seasonal to seasonal (S2S) time scale over Germany. The ensemble hydrological simulations are performed with the mesoscale hydrologic model (mHM) which benefits from a multiscale parameter regionalization module (MPR). The model is forced by the operational ensemble prediction System from the European Center for Medium-range Weather Forecast (ECMWF). 51 hydrological ensemble forecasts are generated in real-time (twice a week) for up to 45 days in advance. We used the initial condition records from the German Drought Monitor (GDM, www.ufz.de/duerremonitor) which provides daily up-to-date high resolution drought information at a spatial resolution of 4 km. The performance of the system is evaluated for three consecutive years started from 2016 for Soil Moisture Index (SMI) and real-time streamflow records (222 based in Zink et al 2017). Comparison between forecasted Soil Moisture Index (SMI) and the one derived by the GDM suggested promising results for certain areas over the study area at S2S time scale. The predictability of the ensemble forecasting system is evaluated against that generated with the Ensemble Streamflow Prediction (ESP) method. This research is one of the first attempts to investigate the hydrological forecasting skill at S2S time scale in Europe. The study is supported as a part of the Modular Observation Solutions for Earth System (MOSES) project.
Full characterization of the ML 5.4 2019/11/11 Le Teil earthquake in France based on a multi-technology approach
Authors: Vallage Amaury , Bollinger Laurent , Cano Yoann , Champenois Johann , Duverger Clara , Hernandez Bruno , Herry Pascal , Le Pichon Alexis , Listowski Constantino , Mazet-Roux Gilles , Menager Marine , Merrer Sophie , Pinel-Puyssegur Béatrice , Rusch Roxanne , Sèbe Olivier , Vergoz Julien , Guilhem Trilla Aurélie
Published: March 2020

Metropolitan France is a region of slow tectonic deformation rates with sparse historical and instrumental seismicity, and where geodesy is not able to reach the required resolution in order to resolve the tectonic loadings. The few faults recognized as potential active rely on rare neotectonic slip rates, often integrated over geological scales.

In this context, the ML 5.4 Le Teil 2019 earthquake is of particular interest because it is the largest seismic event recorded in metropolitan France in the last 16 years. The last regional earthquake with a larger magnitude was the Lambesc event that occurred in 1909 about 110 km away from Le Teil epicenter. This recent earthquake offers a noteworthy opportunity to combine different technologies: seismological observations (RESIF and CEA) with satellite InSAR data and infrasound measurements, to help characterizing this stable continental region.

The analysis shows that the focal mechanism determined from the full waveform inversion of long-period seismological data is consistent with the activation of a reverse fault with a strike around 45°N and is associated with a moment magnitude of 4.8. Moreover, this event produced infrasound signals recorded by the OHP Alpine array located 110 km away. The analysis of these signals provides evidence of ground-to-air coupling in the epicentral region as well as ground shaking information.

Despite the moderate magnitude of the event, the ground deformation is resolved by InSAR with Sentinel-1 data. The interferogram is consistent with the shallow depth inverted from seismology and confirmed by the presence of surface ruptures. The inversion of multiple InSAR tracks allows characterizing the displacement at depth and along strike on the fault plane. The results are consistent with the focal mechanism derived from seismology. The earthquake has ruptured a 5-km long by ~1.5-km deep fault. The displacement reaches a maximum at a shallow 1 km-depth. The source inverted from InSAR coincides with the Rouvière fault, a branch of the Cévennes fault system formerly known as a normal fault. This reverse earthquake might be an example of an inherited structure re-activation as it is often the case in intraplate regions with polyphased history.
Combining palaeontological and geochemical data to reconstruct environmental gradients, a case study from the Jurassic Sundance Seaway
Authors: Danise Silvia , Holland Steven , Price Gregory
Published: March 2020

Environmental gradients are among the primary drivers of change in ecological communities through time and space. However, what is rare are combined data sets of community composition and the environmental factors that may have caused ecological turnover, largely because many environmental variables are difficult to measure in the stratigraphic record. In this study we integrate quantitative abundance estimates of benthic macroinvertebrates with a multivariate dataset of geochemical proxies to potentially estimate the environmental drivers of faunal change through the 13 m.y. history of the Middle–Late Jurassic Sundance Seaway, western United States.

Faunal counts of macroinvertebrates were obtained from marine rocks of the Gypsum Spring, Sundance and Twin Creek formations at 19 localities in Wyoming, Montana and South Dakota. From the same localities, calcitic shells of selected species (Gryphaea planoconvexa, Gryphaea nebrascensis, Gryphaea sp., Liostrea strigilecula, Deltoideum sp.), were analysed for stable isotope (carbon and oxygen) and elemental (Mg/Ca, Sr/Ca, Na/Ca, Ba/Ca) geochemistry. The studied interval was subdivided into seven third-order depositional sequences representing carbonate ramp, wave-dominated, siliciclastic shelf, siliciclastic tidal coast, and mixed evaporite-siliciclastic desert systems. Of these, five depositional sequences were fossiliferous.

Ordination plots (nMDS) of the two palaeoecological and geochemical datasets are very similar (procrustes correlation: 0.75, p: 0.0001). Vector fitting of geochemical data on the palaeoecological ordination shows that a main faunal turnover event, corresponding to the shift from carbonate to siliciclastic deposition at the Middle–Late Jurassic transition, correlates with an increase in productivity (increase of δ13C) and a decrease in temperature (decrease of Mg/Ca ratio) through time. Position of fauna in the seaway (craton vs. foredeep) correlates instead with variations of δ18O and Ba/Ca ratio, suggesting a strong salinity gradient, with decreasing salinity moving from the craton towards the foredeep. A critical discussion of these results will also include factors that could potentially affect temporal changes of proxy data, such as species-specific vital effects.
Statistical analysis for the identification of precursory signatures of earthquake occurrence in Total Electron Content (TEC)
Authors: Colonna Roberto , Tramutoli Valerio , Filizzola Carolina , Genzano Nicola , Lisi Mariano , Pergola Nicola
Published: March 2020

In the last few decades several parameters (chemical, physical, biological, etc.) have been proposed in association with the complex process of preparation of earthquakes. In particular, the variability of space weather has been proposed, since long time, as possible indicator of impending earthquakes. This variability can be optimally captured by the detection of anomalous Ionospheric-Total Electron Content (TEC) variations.

The investigation of the preparation phase of past strong earthquakes could be useful to understand the physical processes involved and to develop a future short-term warning system.

Since 2001, the general change detection approach RST (Robust Satellite Techniques; Tramutoli, 1998; 2005; 2007) has been used to discriminate anomalies in Earth’s thermal emission measured by satellite possibly associated to seismic activity, from normal fluctuations of the signal related to other causes (e.g. meteorological) independent on the earthquake occurrence.

In this work are shown the results about the use of a RST-based approach for the preseismic TEC anomalies identification.

The RST methodology has been reformulated and adapted in order to be applied to TEC measurements recorded by the GPS satellite constellation, so as to discriminate anomalous signals from normal fluctuations of the signal itself. To this aim, we studied the behavior of the TEC parameter, proceeding to the construction of a multi-year dataset of observations (>5 years) in Mediterranean seismically active areas, both in presence and in absence, of strong seismic events (M≥5).

The achieved results are discussed and compared with the results obtained through independent RST analyses carried out on the Earth’s Thermal Infrared Radiation (TIR) parameter. The comparison of the results obtained using the two parameters is made in order to evaluate how the joint use of both parameters (TEC and TIR) in the framework of a multi-parametric approach can improve the present capability of detection of these perturbations.
Temporal shifts in erosion provenance through multiple earthquake cycles
Authors: Wang Jin , Howarth Jamie , McClymont Erin , Densmore Alexander , Fitzsimons Sean , Croissant Thomas , Gröcke Darren , West Martin , Harvey Erin , Frith Nicole , Garnett Mark , Hilton Robert
Published: March 2020

Landslides are a dominant mechanism of erosion in mountain landscapes. Widespread triggering of landslides by large storms or earthquakes can lead rapid changes in short-term erosion rates. If landslides occur repeatedly in particular parts of a mountain range, then they will dominate the evolution of that section of the landscape and could leave a fingerprint in the topography. Despite this recognition, it has proved difficult to examine shifts in the focus of landslide erosion through time, mainly because remote sensing approaches from single events to a few decades at most. Here we turn to the depositional record of past erosion, attempting to track landslide occurrence and the provenance of eroded material using a novel combination of the isotopic and molecular composition of organic matter (bulk C and N isotopes, molecular abundance and isotopic composition) deposited in Lake Paringa, fed by catchments proximal to the Alpine Fault, New Zealand. In the modern day forest, we find correlations between elevation, soil depth and the bulk δ13C values of the organic matter and the carbon preference index of n-alkanes. We find large shifts in these measurements in the lake core. Using an empirical model based on modern soil samples we suggest that the erosion provenance shifts dramatically after each of four large Alpine Fault earthquakes in the last one thousand years. These shifts in inferred erosion altitude match shifts in the hydrogen isotope composition of long-chain n-alkanes (plant wax biomarkers) and the inferred shifts in depth track changes in organic matter radiocarbon activity and nitrogen isotope composition, lending support to our model. The combination of bulk isotopic composition and biomarker ratios has the potential to track erosion provenance in other settings. In the Lake Paringa record, we find that post-seismic periods eroded organic matter from a mean elevation of 722 +329/-293 m at the headwaters of source catchments and supplied 43% of the sediment in the core, while inter-seismic periods sourced organic matter primarily from lower elevations (459 +256/-226 m). These results demonstrate that repeated large earthquake consistently focus erosion at high elevations, while inter-seismic periods appear less effective at modifying the highest parts of the topography. 
Tectonic, erosional and climatic controls on sedimentary basin evolution a case study from the Tropoja Basin (Albania)
Authors: Gemignani Lorenzo , Simon Daniel , Mittelbach Benedict , Hippe Kristina , Handy Mark, R.
Published: March 2020

River terraces located in the Tropoja Basin in northern Albania are characterized by high elevation (c. 600 m) and by multiple incision events that highlight the interaction between tectonically induced surface uplift, glaciation, and erosion. The Tropoja Basin is located in the hanging wall of the Shkoder-Peja Normal Fault (SPNF) a crustal-scale normal fault trending orthogonal to the strike of the Dinarides Belt. Neo-tectonic activity along the SPNF is indicated by several recent earthquakes. Glaciated valleys drain into the upper reaches of the Valbona River draining the basin. The processes regulating the evolution of the basin infill and the incision of the river terraces remain unclear.

Our mapping reveals that the Pliocene basin fill is overlain by two sub-horizontal layers of Pleistocene-Holocene sediment: porous conglomerate below and red clay above. The conglomeratic layer contains components derived mostly from Mesozoic limestones in Dinaric nappes in the glacial Valbona and Gashi Valleys. The drainage direction in the basin inferred from paleo flow indicators in both layers was to the SW, i.e., in the direction of present-day flow into the Drini Gorge that cuts down to the Adriatic coast. In addition, we recognize three terrace levels in these sediments, the top two of which are carved by abandoned river channels. The terraces and channels cut across the Pleistocene-Holocene layer contacts and are therefore younger than the layers’ deposition. The layers themselves thicken away from the SPNF, and show no preferred dip toward or away from the SPNF. Work is underway to date these terraces with cosmogenic nuclides.

Initial relief leading to the Pliocene infill of the Tropoja Basin is interpreted to be a by-product of SPNF activity, which began already in mid-Miocene time. However, this activity is insufficient to explain post-Pliocene sedimentation in the Tropoja Basin because the thickness and dip of the Pleistocene-Holocene layers do not vary systematically with proximity to the SPNF. We, therefore, interpret the Pleistocene-Holocene basin fill to be glacial, with the basal porous conglomerates deposited during sudden out washing of the glacial valleys due to release of melting water behind moraine dams. The overlying red clay layer is interpreted to be a lacustrine deposit due to damming further down the Drini Valley. The preservation of abandoned stream channels in the terraces may reflect episodic uplift and fluvial down-cutting events. The down-cutting may be attributed either to isostatic uplift of the upper plate of the retreating Hellenic subduction and/or to interglacial unloading.
Rainfall induced-landslides and man-made landforms mapping for underground utility networks management in a mediterranean metropolitan area (Genoa, Northwest Italy)
Authors: Terrone Martino , Marchese Alessandra , Bazzurro Nicola , Faccini Francesco
Published: March 2020

Extreme precipitation has become increasingly frequent in the last years in Liguria, a hilly and mountainous region in Nortwest Italy. In particular, the Genoa metropolitan area is internationally known for rainfall ground effects: from the beginning of this millennium four intense flash floods have been recorded and as many rainfall-induced landslide periods with significant impacts in roads, buildings and underground utility networks.

These phenomena are also related with more than a century of urbanization that has completely changed landforms and increased the vulnerability of the area.

The research consists of preliminary study based on the production of three different maps: Landslide inventory map, Landslide susceptibility zoning map and a preliminary Man-made landform map that could help to describe better the Urban Geomorphology of Genoa metropolitan area, characterized by isolated and spread houses laying on terraced slopes mixed with high density urban area with aged decametric retaining walls.

On site monitoring, satellite interferometric data and historical maps were used to support the production of cartography work.

In a second step, the above maps were associated with underground utility networks (water and energy) categorized by age, diameter and material to know the potential failure risks induced both by geomorphological and structural factors.

Thanks to this research underground assets management is expected to be more efficient, determining priorities for actions in areas with higher risk.
Do spatial patterns of water and matter fluxes below the main rooting zone depend on canopy processes?
Authors: Hildebrandt Anke , Bock Stephan , Fischer Christine , Metzger Johanna , Weckmueller Joseph , Demir Goekben
Published: March 2020

Besides precipitation also atmospheric deposition is modified by canopy processes. By passing the canopy, precipitation water washes out those deposited compounds and creates substantial heterogeneity of input of dissolved matter at the forest floor. At the same time, both dry atmospheric deposition of aerosols and net precipitation are affected by canopy heterogeneity, like variation in canopy density. In consequence, spatial patterns of both dry and wet deposition are expected to vary strongly in space and to depend on canopy structure, which may lead to hotspots of input and deep drainage. However, few studies so far have investigated the spatial patterns of deposition of e.g. nitrogen compounds. In this research we investigated the spatial and temporal patterns of nitrogen deposition and export from the main rooting zone in a beech dominated forest in the Hainich National Park.

 

We find that below canopy spatial patterns of both canopy drainage and nitrogen deposition show some temporal stability. Spatial variation in canopy drainage also affected soil water percolation in 30 cm depth, with higher canopy drainage leading to higher soil water fluxes. Nitrogen deposition at the forest floor however, seemed rather driven by canopy exchange than by drainage patterns or dry deposition. On the other hand, at 30 cm soil depth nitrogen export in seepage water was driven by the soil water flow, indicating that spatial patterns of transport capacity, and not nitrogen availability in the soil, determined the export of nitrogen from the main rooting zone. Interestingly, spatial variation of soil water fluxes was not dampened, but rather increased by passage of the rooting zone. In other words, the origin of spatial patterns of water flow and nitrogen export below the main rooting zone lay already within the canopy, but was further enhanced in the soil. The next steps will be to understand why the heterogeneity of water fluxes propagates and increases during rooting zone transit and whether there is an interaction with soil development.
Are Collembola flying onto green roofs?
Authors: Joimel Sophie , Vieublé-Gonod Laure , Grard Baptiste , Chenu Claire
Published: March 2020

Are Collembola flying onto green roofs?  

With a worldwide urban population projected to reach 5 billion by 2030 (Véron, 2007), the roles and benefits of urban green spaces cannot be denied, like climate regulation by trees or water flow regulation (Gómez-Baggethun and Barton, 2013). If green spaces are among the new societal expectations of urban people, they also play a crucial role in preserving biodiversity in urban areas. Among them, green roofs are a great opportunity to create green space in cities as they represent 32% of cities’ horizontal surfaces (Frazer, 2005). Their installation is also perceived as a possible way to preserve biodiversity in cities. However, the effectiveness of green roofs in supporting biodiversity, especially soil biodiversity, has rarely been studied.

Thanks to different research programmes (TROL, SEMOIRS and T4P), we investigated the taxonomic and functional collembolan biodiversity in both extensive and productive green roofs as well as in ground-level urban microfarms in order to (i) evaluate the effectiveness of green roofs in supporting soil biodiversity, (ii) identify the mechanisms of colonisation by soil organisms and (iii) separate the effect of landscape and soil conditions on collembolan communities assemblages.

Surprisingly, green roofs are supporting high levels of soil biodiversity. Despite various soil characteristics (organic matter and water avaibility), no difference was found between extensive roofs and rooftop gardens concerning the taxonomical structures of collembolan communities (e.g. species richness, abundances). In contrast, there are differences concerning both taxonomic and functional compositions. Two ways of colonisation are suggested: a passive wind dispersal − the “flying” collembolans − and a settlement through compost inputs. We conclude that stakeholders should take into account the spatial connections of green roofs with other green spaces in order to support urban soil biodiversity.
Gravity wave intermittency derived from HIRDLS and SABER satellite limb soundings
Authors: Ern Manfred , Preusse Peter , Riese Martin
Published: March 2020

Sources of atmospheric gravity waves are mostly located in the troposphere and the lower stratosphere. Gravity waves propagate away from their sources, re-distribute energy and momentum in the atmosphere, and exert drag on the atmospheric background flow where they dissipate. Therefore they are important drivers of the atmospheric circulation. In climate models, their effect on the background circulation is usually parameterized because of their relatively short horizontal and vertical wavelengths that are of the order of 10-1000km and 1-100km, respectively. Gravity wave parametrizations are very simplified. For example, they often neglect the fact that gravity wave source processes and gravity wave propagation conditions can vary on short temporal and spatial scales. Therefore the global distribution of gravity wave activity is very intermittent, which has also important consequences where gravity waves dissipate and exert drag on the background flow, and which should be accounted for in parametrizations.
For guiding models, global observations of the gravity wave distribution and its intermittency are needed. We derive gravity wave potential energies and absolute momentum fluxes from observations of the High Resolution Dynamics Limb Sounder (HIRDLS) and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite instruments. As a measure of intermittency, we calculate global distributions of Gini coefficients. We find that our results are qualitatively in good agreement with previous findings from satellite, and similar in magnitude to intermittency obtained from previous superpressure balloon campaigns. In the stratosphere, strongest intermittency is found over orographic gravity wave sources, followed by gravity wave activity in the polar night jets. Intermittency in the tropical stratosphere is weakest. However, in the tropical upper mesosphere intermittency is increased, which is likely caused by the modulation of the gravity wave distribution by tides.
Antarctic Peninsula mass trends from 2003 - 2016 using a Bayesian hierarchical model approach
Authors: Chuter Stephen , Rougier Jonathan , Dawson Geoffrey , Bamber Jonathan
Published: March 2020

Long-term continuous monitoring of Antarctic Ice Sheet mass balance is imperative to better understand its multi-decadal response to changes in climate and ocean forcing. Additionally, more accurate knowledge of contemporaneous mass balance is key for improved parameterisations in ice sheet models. The Antarctic Peninsula has undergone rapid changes in mass balance and ice dynamics over the last two decades, with satellite observations showing the presence of grounding line retreat and increases in ice sheet velocity. This is particularly the case after the collapse of the Larsen A and B ice shelves in 1995 and 2002, and more recently the glaciers draining the southern Antarctic Peninsula. As a result, this region provides analogues for future ice sheet response to ice shelf collapse in other regions of Antarctica. 

Despite the region’s importance to understanding ice sheet dynamics, it is challenging to accurately assess mass balance due its geometry and mountainous topography. Conventional pulse-limited altimetry suffers from poor coverage and data loss over steep mountainous terrain, particularly before the launch of CryoSat-2 in 2010. In the case of gravimetry, the geometry of the region means the coarse spatial resolution of the GRACE mission (~300 km) cannot resolve small spatial scale glacier changes (particularly over northern Antarctic Peninsula) and suffers from signal leakage into the ocean. For the mass budget approach, the challenge of accurately modelling surface mass balance over the region’s mountainous topography coupled with the sparsity of ice thickness observations at the grounding line for many sectors can result in large uncertainties. As a result, it can be difficult to reconcile the results from different conventional approaches in this region. 

To resolve this, we have developed and optimised the BHM framework used previously over the Antarctic Ice Sheet to specifically investigate the Antarctic Peninsula. This enables each latent process driving ice sheet mass change to be resolved at a higher spatial resolution compared to previous implementations across Antarctica as a whole. The new regional solution also incorporates more recent and higher resolution observations including: CryoSat-2 swath altimetry, stereo-image DEM differencing and NASA Operation Ice Bridge laser altimetry elevation rates. This is the first time such a range of observations of varying spatio-temporal resolutions will be combined into one assessment for the region. We will present results from the regionally optimised model from 2003 until present, including basin-scale mass trends and changes in spatial latent processes at an annual resolution. Additionally, we will discuss future opportunities, such as extending the record from this approach into the next decade and further understanding of the GIA response in this region. 
Sensitivity of the WRF – HAILCAST model to microphysics and PBL parameterization shemes
Authors: Malečić Barbara , Jelić Damjan , Horvath Kristian , Babić Karmen , Mikuš Jurković Petra , Strelec Mahović Nataša , Telišman Prtenjak Maja
Published: March 2020

Hail is a significant convective storm hazard in Croatia, often causing property and crop damage. The existing analysis, based on hailpad network data, shows that western and central regions of Croatia have a significant frequency of high-intensity hail events.

Advances in computational power and recent developments in atmospheric modeling have enabled the use of convection-permitting models (CPM) that can partially resolve deep convective events such as thunderstorms and rain showers. However, hail remains a difficult phenomenon to model or forecast since CPMs are still not able to fully resolve processes involved in producing hail. One way to address this issue is by embedding a physically-based one-dimensional hail model called HAILCAST within a CPM. Here, the HAILCAST model is embedded within the Weather Research and Forecasting (WRF) model.

The selected hail event is analyzed using WRF-HAILCAST model simulations. HAILCAST forecasts the maximum expected hail diameter using a profile of the vertical updraft, temperature, liquid and ice water content from a given WRF timestep and grid columns. Here, a set of numerical convection-permitting experiments are performed to assess the sensitivity of the results to different microphysics and planetary boundary layer (PBL) parameterization schemes and to provide guidance for WRF-HAILCAST tuning. The results are verified by observational (hailpad, hail observations) data as well as with radar, lightning and satellite measurements where available.
NoeTALUS - Methods for producing rock fall hazard maps of different scales in Lower Austria
Authors: Preh Alexander , Glade Thomas , Koçiu Arben , Fleris Emmanouil , Illeditsch Mariella , Mergili Martin , Marlovits Nina , Schweigl Joachim , Bertagnoli Michael
Published: March 2020

For regions with distinct rock cliffs, rock fall represents a serious hazard due to high propagation velocities. In order to pursue territorial planning with an awareness of rock fall hazard, it is necessary to identify those areas that are or may be affected by this process. A detailed analysis of rock fall hazard (at regional or municipal scale) represents a great challenge, as many parameters that are difficult to quantify in the field must be considered (e.g. block sizes, surface conditions, etc.).

The aim of the ongoing “NoeTALUS – Rock fall hazard modelling in Lower Austria” research project is to evaluate and suggest methods, applicable to different scales, which will enable the production of reliable rock fall hazard maps at a justifiable amount of human and financial resources.

Rock fall hazard maps are being prepared for two pilot areas in Lower Austria: the municipality of “Dürnstein” and the western part of the municipality of “Waidhofen an der Ybbs”. In order to answer questions regarding the required quality and effort in collecting data relevant to numerical modelling, investigations under two topographic scales are being conducted. The entire project area is processed at a regional scale (M ≤ 1:10.000). Additionally, ten selected domains within the project area are investigated at a slope scale (M ≥ 1:5.000). In this context, remote sensing methods (LiDAR, photogrammetry) are to be evaluated with regard to their benefits.

Two different simulation models, Rockyfor3D and WURF3D, are used to model rock fall spreading and magnitude. Both models differ in their calculation approach with regard to surface-roughness, energy-damping and rock fragmentation.

Rock fall simulations are being evaluated by comparing observed and calculated deposits. Relevant indicators such as the Critical Success Index, Factor of Conservativeness, or area under ROC are being employed for this task.

The selected approach is intended for identifying those methods that can contribute to the creation of reliable rock fall hazard maps at a reasonable cost. Finally, “recommendations for action” concerning the production of rock fall hazard maps are to be made based upon the comparison of different methodologies.
The potential of satellite data to calculate the global OH distribution using simplified steady state approximations
Authors: Pimlott Matilda , Chipperfield Martyn , Pope Richard , Kerridge Brian , Siddans Richard
Published: March 2020

The hydroxyl radical (OH) is one of the most important species in atmospheric chemistry. It plays a dominant role in the oxidation of many other species in the troposphere, such as anthropogenic pollutants. Direct in-situ and satellite measurements of OH are scarce due to its short lifetime (around 1 second) and low abundance. Other indirect methods of inferring global mean OH have been established, such as using methyl chloroform as a tracer. However because of its recent phase out there is a demand for another method of calculating the global OH abundance. It is therefore useful to explore indirect methods for calculating OH. In particular, global satellite data can provide a means for estimating mean OH within large atmospheric regions. An improved understanding of the global distribution of OH will allow a better understanding of atmospheric chemistry, especially the distributions of anthropogenic pollutants.  

Due to the short lifetime of OH, a steady-state approximation can be used to model its concentration. This allows the OH distribution to be calculated using a simple equation and the accuracy of the estimate depends on the number of source/sink terms which can be included in the equation. In this work, a steady state approximation has been applied to the global OH budget as defined in the TOMCAT 3-D model. The full steady-state equation (based on all reactions in the model) has been simplified in various ways to include only the major sources and sinks of OH that can be observed directly by satellite, such as carbon monoxide (CO), methane (CH4), water vapour (H2O) and ozone (O3). 

Recent satellite observations of these species is then applied to the steady-state approximation to derive an estimate of the global OH distribution. We use the 3-D model to determine where the simplified steady-state approximation is likely to be most valid. The overall potential of this method to calculate an accurate OH distribution, bearing in mind satellite observation errors, is discussed. 
Surface thermal inversion evolution in the bottom of a Pyrenean valley studied by observations and mesoscale simulations
Authors: Jiménez Maria A. , Cuxart Joan , Paci Alexandre , Conangla Laura , Martínez-Villagrasa Daniel , Martí Belen
Published: March 2020

Two experimental campaigns have been carried out in the Cerdanya valley at south side of the Pyrenees (E-W oriented, 35 km long and 9 km wide) during fall 2015 (Cerdanya Cold Pool experiment, CCP’15) and winter 2017 (CCP’17, as a part of the Cerdanya-2017 experiment) to study the cold pool that usually forms there at night. The main site (Das) is placed in the central bottom part of the basin. Conangla et al (2018, IJOC) showed that most cold pool events reported there have a daily cycle, being formed in the evening and destroyed by solar heating of the surface the morning after.

The availability of vertical soundings performed by a tethered balloon and a WindRASS, together with measured surface fluxes of latent and sensible heat and momentum at the surface layer allows to inspect the establishment and evolution of the surface thermal inversion in Das. This area collects also downslope and downvalley flows accumulating cold air in the valley along the night. The organization of the flow at low levels is studied through mesoscale simulations of some selected Intensive Operational Periods (IOPs) and the surface observations at different locations along and across the valley.

The selected IOPs comprise nights with only locally-generated winds and small cloud cover, and with variable surface state including grass, fresh snow and patches of old snow. The evolution of the strength and depth of the surface inversion as seen by the model are compared to the available data. Besides, the organization of the flow at low levels and the contribution of the air from the tributary valleys is analyzed in terms of temperature and wind speed budgets to properly characterize the differences in the strength of the cold pool for the selected studied IOPs.
Conditions for the Compost Bomb Instability
Authors: Clarke Joe , Ritchie Paul , Cox Peter
Published: March 2020

Under global warming, soil temperatures are expected to rise. This increases the specific rate of microbial respiration in the soils which in turn warms the soil, creating a positive feedback process. This leads to the possibility of an instability, known as the compost bomb, in which rapidly warming soils release their soil carbon as CO2 to the atmosphere, accelerating global warming. Models of the compost bomb have exhibited interesting dynamical phenomena: excitability, rate induced tipping and bifurcation induced tipping. We examine models with increasing degrees of sophistication, to help understand the conditions that give rise to the compost bomb. We clarify the role an insulating moss layer plays and demonstrate that it has a 'most dangerous' thickness. We also use JULES, a land surface model, to examine where a compost bomb might occur and what affect other processes such as hydrology might have on the compost bomb.
The impact of tidal dissipation changes on the Last Glacial Maximum AMOC
Authors: Wilmes Sophie-Berenice , Green Mattias , Schmittner Andreas
Published: March 2020

The global mean sea-level decrease of 120 – 130 m during the Last Glacial Maximum (LGM; 26 – 19 kyr BP) is thought to have substantially altered semidiurnal tidal dynamics in the glacial North Atlantic. This more than doubled global open ocean tidal dissipation in comparison to present day and increased the amount of energy available for diapycnal mixing which is important for driving the global meridional overturning circulation. Reconstructions of the glacial ocean have generally suggested a more sluggish Atlantic meridional overturning circulation (AMOC) during the LGM together with weaker mixing. Here, we investigate the impact of tidal dissipation changes on the LGM AMOC and the carbon cycle using the intermediate complexity ocean model UVic coupled to the biogeochemistry model MOBI forced with three different LGM dissipation estimates. The simulations are constrained with LGM δ13C and radiocarbon data from sediments. Our results suggest that our simulations, as previously inferred, most closely agree with a weakened LGM AMOC (8 – 9 Sv), and importantly, that the agreement is consistent with increased LGM tidal mixing. These results firstly imply that a weakened AMOC state can occur with stronger tidal mixing without hampering the agreement with the sediment isotope data. Secondly, this work highlights the importance of considering tidal dissipation changes when modelling the paleo-ocean.
Proactive optical monitoring of catchment dissolved organic matter for drinking water source protection
Authors: Weatherill John , Fernandez-Pascual Elena , O'Dwyer Jean , Gilchrist Elizabeth , Harrison Simon , Goslan Emma , Khamis Kieran , O’Driscoll Connie
Published: March 2020

Ireland has a far greater number of regulatory exceedances for trihalomethanes (THMs) in public water supplies than the next highest European Union member state. In Ireland, 82% of public water supplies originate from surface water catchments which require disinfection to inactivate pathogens and prevent the spread of waterborne diseases. Since the 1970s, it has been known that the use of chlorine for disinfection leads to the formation of potentially harmful disinfection byproducts (DBPs) of which some are suspected carcinogens. THMs are one prominent class of at least 700 potentially harmful disinfection byproducts (DBPs) produced after chlorination of dissolved organic matter (DOM) present in source water which is not removed prior to disinfection.

We introduce a new research project, funded by the Irish Environmental Protection Agency entitled PRODOM: PRoactive Optical monitoring of catchment Dissolved Organic Matter for drinking water source protection. The overall aim of the research is to develop an integrated catchment-level understanding of the spatiotemporal dynamics of DOM precursors and associated DBP formation risk. The project will explore the relationship between optically-active DOM precursors and laboratory formation potentials for key DBPs including emerging classes of potentially more harmful nitrogenous DBPs. Through high-resolution spatial sampling we will develop geospatial DBP formation risk maps and identify risk-driving point and diffuse precursor sources. We will evaluate the potential of state-of-the-art UV fluorescence sensor technology to act as an early warning tool for proactive management of source water at sub-catchment scale. Using high-frequency time series monitoring of fluorescent precursors, we will identify high-risk periods in the catchment hydrograph and evaluate critical precursor sources and pathways to inform a series of catchment management measures designed to reduce DBP formation risk. 