bluuebunny/crossref_metadata_2025 huggingface dataset:
Long term changes in the deep sea: examples from two Mediterranean Channels
Authors: Schroeder Katrin , Ben Ismail Sana , Chiggiato Jacopo , Borghini Mireno , Sparnocchia Stefania
Published: March 2020

Climate change is one of the key topics of our century. The study of processes related to climate change in the atmosphere, the open ocean, the deep sea or even in shallow coastal waters require sustained long-term observations, often deploying sophisticated and expensive equipment. According to the Deep-Ocean Observing Strategy (DOOS, http://deepoceanobserving.org/), the deep ocean (below 200 m water depth) is the least observed, but largest habitat on our planet by volume and area. With more than 90% of anthropogenic heat imbalance absorbed by the oceans, monitoring long-term changes of its heat content, and over its full depth, is essential to quantify the planetary heat budget.

The Mediterranean Sea is a mid-latitude marginal sea, particularly responsive to climate change as reported by recent studies. Straits and channels divide it into several sub-basins and the continuous monitoring of these choke points allows to intercept different water masses, and thus to document how they changed over time. This monitoring, in many cases, is done under the umbrella of the CIESM Hydrochanges program (http://www.ciesm.org/marine/programs/hydrochanges.htm). Here we report the long-term time series of physical data collected in two of these choke points: the Sardinia Channel (1900 m) and the Sicily Channel (400 m).

The Sardinia Channel allows the Western Mediterranean Deep Water (WMDW) to enter the Tyrrhenian Sea (depths > 3000 m), connecting it with the Algerian Sea (depths > 2500 m). This water mass has experienced a significant increase of heat and salt content over the past decades, due both to a gradual process and to and abrupt event, called Western Mediterranean Transition (WMT). The monitoring at the sill (1900 m) of the Sardinia Channel since 2003 shows this very clearly, and the interannual trends are significantly stronger than the global average trends.

The Sicily Channel (sill at 400 m) separates the Mediterranean in two main basins, the Eastern Mediterranean Sea and the Western Mediterranean Sea. Here the thermohaline properties of the Intermediate Water (IW) are monitored since 1993, showing increasing temperature and salinity trends at least one order of magnitude stronger than those observed at intermediate depths in the global ocean.

We investigate the causes of the observed trends and in particular discuss the role of a changing climate over the Mediterranean, especially in the eastern basin, where the IW is formed. The long-term records in two Mediterranean channels reveal how fast the response to climate change can be in a marginal sea compared to the global ocean, and demonstrates the essential role of long time series in the ocean.
Land use change from an annual maize cropping systems to a perennial Silphium perfoliatum crop has unused potential to reduce GHG emission in biomass production
Authors: Kemmann Björn , Ruf Thorsten , Kirch Andreas , Emmerling Christoph , Fuß Roland , Well Reinhard
Published: March 2020

In the last two decades, acreage for biomass production has strongly increased in Germany due to the Renewable Energy Act. Recently, discussion about soil, climate, and biodiversity protection is receiving more and more public attention throughout broad parts of the society. The project BESTLAND focuses on the effect of land use change from the common annual maize cropping system to a perennial cropping system, as a measure against increasing environmental constraints in biomass production. A suitable perennial biomass crop as an alternative for maize is S. perfoliatum (cup plant). On one hand, the yellow flowering plant produces high biomass yields and on the other hand it provides a variety of ecosystems services. Field experiments were carried out in the Saar-Nahe mountain range in the state of Saarland on a fine textured planosol. The experimental sites are characterized by temporal waterlogging and slopes and therefore these sites are prone for soil compaction and soil erosion. Under these conditions perennial crops are assumed to have soil preserving benefits. Maize was compared to cup plant by establishing four paired sites, where each pair consisted of a maize and a cup plant field in close vicinity (< 500 meters) to each other. All sites are grower fields and were managed by the farmers according best management practices. Nitrous oxide and methane fluxes were measured weekly using the static chamber technique all year round. Besides greenhouse gas measurement, soil samples for determination of soil mineral nitrogen were taken at each gas sampling date. Furthermore, soil temperature and water content were continuously monitored using sensors. Biomass yields at each site were determined at harvest. In the first year average nitrous oxide emissions from cup plant fields were lower than from maize fields by more than 70 % on area and dry matter yield basis. These results indicate that perennial bioenergy crops not only offer a wider range of ecosystem services but can also decrease GHG emissions from bioenergy production.
Advances in field data collection in volcano-tectonic sensitive areas: examples and results from the Northern Volcanic Zone of Iceland
Authors: Bonali Fabio Luca , Tibaldi Alessandro , Pasquaré Mariotto Federico , Russo Elena , Corti Noemi
Published: March 2020

Classical field studies are vital for mapping and understanding volcano-tectonic processes, particularly for those that produce superficial deformation consequently to magmatic and tectonic activity. Unfortunately, very often, key outcrops are inaccessible due to harsh logistic conditions or their location in remote or dangerous areas. In the framework of the ILP Task Force II, we developed and tested modern and innovative methods aimed at overcoming these limitations in field research and data collection, that we combined with classical field mapping. Such methods have been used to provide a more complete picture of the deformation processes that have been taking place in the Theistareykir Fissure Swarm within the Northern Volcanic Zone of Iceland. This rift is characterized by the presence of huge normal faults, several extension fractures and volcanic centres. The modern methods we used derive from the use of UAVs (drones) combined with Structure from Motion (SfM) photogrammetry techniques. The first innovative method consists of analysing UAV-based SfM-derived high resolution orthomosaics and digital surface models where we collected hundreds of quantitative measurements of the amount of opening and opening direction of Holocene extension fractures and measurements of fault scarp height. The second and more innovative method we used is the Immersive Virtual Reality that can be applied to 3D digital outcrop models (DOMs), reconstructed with UAV-based SfM photogrammetry techniques; several sites within the Theistareykir Fissure Swarm have been reconstructed in the framework of the Italian Argo3D project. The reconstructed 3D DOMs were explored using different modalities: on foot, as is often the case during field activity, moving like a drone, above and around the target, as well as flying like an airplane. Thanks to these modes of exploration we were capable of better understanding the geometry of extension fractures, volcanic centres and normal faults. We also measured, in the virtual environment, the opening direction and the amount of dilation along the extensional fractures, the direction of magma-feeding fractures underlying cones and volcanic vents, as well as the amount of vertical offset along normal faults. The quantification and mapping of these features was accomplished through some tools tailored for virtual field activity in the framework of Italian Argo3D project and the Erasmus+ Key Action 2 2017-1-UK01-KA203-036719. Thanks to the merging of classical and modern approaches we are able of providing a complete picture related to the post-LGM deformation field affecting this part of the Icelandic rift, particularly focusing on the spreading direction and the stretch ratio across the whole Theistareykir Fissure Swarm.
A weighting scheme to incorporate large ensembles in multi-model ensemble projections
Authors: Merrifield Anna , Brunner Lukas , Lorenz Ruth , Knutti Reto
Published: March 2020

Multi-model ensembles can be used to estimate uncertainty in projections of regional climate, but this uncertainty often depends on the constituents of the ensemble. The dependence of uncertainty on ensemble composition is clear when single model initial condition large ensembles (SMILEs) are included within a multi-model ensemble. SMILEs introduce new information into a multi-model ensemble by representing region-scale internal variability, but also introduce redundant information, by virtue of a single model being represented by 50–100 outcomes. To preserve the contribution of internal variability and ensure redundancy does not overwhelm uncertainty estimates, a weighting approach is used to incorporate 50-members of the Community Earth System Model (CESM1.2.2), 50-members of the Canadian Earth System Model (CanESM2), and 100-members of the MPI Grand Ensemble (MPI-GE) into an 88-member Coupled Model Intercomparison Project Phase 5 (CMIP5) multi-model ensemble. The weight assigned to each multi-model ensemble member is based on the member's ability to reproduce observed climate (performance) and scaled by a measure of historical redundancy (dependence). Surface air temperature (SAT) and sea level pressure (SLP) diagnostics are used to determine the weights, and relationships between present and future diagnostic behavior are discussed. A new diagnostic, estimated forced trend, is proposed to replace a diagnostic with no clear emergent relationship, 50-year regional SAT trend.

The influence of the weighting is assessed in estimates of Northern European winter and Mediterranean summer end-of-century warming in the CMIP5 and combined SMILE-CMIP5 multi-model ensembles. The weighting is shown to recover uncertainty obscured by SMILE redundancy, notably in Mediterranean summer. For each SMILE, the independence weight of each ensemble member as a function of the number of SMILE members included in the CMIP5 ensemble is assessed. The independence weight increases linearly with added members with a slope that depends on SMILE, region, and season. Finally, it is shown that the weighting method can be used to guide SMILE member selection if a subsetted ensemble with one member per model is sought. The weight a SMILE receives within a subsetted ensemble depends on which member is used to represent it, reinforcing the advantage of weighting and incorporating all initial condition ensemble members in multi-model ensembles.
Identification of potential methane source regions in Europe using d13C-CH4 measurements and back trajectory modeling
Authors: Varga Tamás , Haszpra László , Major István , Nisbet Eugan G. , Lowry David , Fisher Rebecca E. , Jull Timothy A.J. , Molnár Mihály , László Elemér
Published: March 2020

A three-year-long methane mole fraction and d13CCH4 measurement campaign was performed at the Hungarian tall tower station, Hegyhátsál, between 2013-2016. The results were compared with that of two NOAA atmospheric monitoring sites Mace Head and Zeppelin to determine the continental methane excess and the relative isotopic shift. The data then were used for bac trajectory analyses to identify potential methane source regions in Europe coupled with d13CCH4 results. The Hungarian station can be separated from the coastal and polar areas based on the mole fraction results having higher maxima and seasonal amplitude, but the d13CCH4 results match well with the NOAA stations’ results. Our study shows that although the local, regional anthropogenic and natural sources are major influences, more distant regions can also influence the measured CH4 level and d13CCH4 signal in the Pannonian Basin.
Validation of Earth rotation time series by comparison of their sub-daily to sub-monthly excitation signal with simulated geophysical fluid model excitations
Authors: Dill Robert , Dobslaw Henryk , Thomas Maik , Hendrik Hellmers , Daniela Thaller , Mathis Bloßfeld , Alexander Kehm , Florian Seitz
Published: March 2020

Time-variations in the orientation of the solid Earth are largely governed by the exchange of angular momentum with the surface geophysical fluids of atmosphere, oceans, and the land surface. Modelled fields of atmospheric winds, atmospheric surface pressure, ocean currents, ocean bottom pressure, and terrestrial water storage allow calculating effective angular momentum (EAM) functions that can be compared to geodetic angular momentum functions (GAM) derived from observed Earth Orientation Parameters (EOP) via the Liouville equation. Especially in the high-frequency range, currently available global geophysical fluid models provide highly reliable information about angular momentum transfers that determine the orientation changes of the Earth.

In this contribution, we investigate the extent to which the modelled Earth rotation angular momentum functions processed at GFZ can be used to evaluate time series of EOP processed from different geodetic space techniques at periods between 2 and 60 days. We therefore compare the time series from various sources that are based on individual techniques (e.g., VLBI[TD1], GNSS, SLR, and DORIS) only, and also combined solutions that are processed at different institutions (e.g., JPL, GFZ, BKG[TD2], DGFI-TUM) or published by international services (e.g., IERS, IGS, IVS[TD3] ). By calculating differences from all possible pairs of EAM and GAM and by utilizing both band-pass filtering and spectral analysis techniques, we will elaborate the systematic differences between excitation functions from different sources that are expected to help identifying deficits in geodetic data processing and/or numerical modelling.
The geochemical riddle of Mediterranean low-salinity gypsum deposits
Authors: Aloisi Giovanni , Natalicchio Marcello , Guibourdenche Laetitia , Caruso Antonio , Dela Pierre Francesco
Published: March 2020

Large deposits of gypsum accumulated in the marginal basins of the Mediterranean Sea during the Messinian Salinity Crisis. These form the marginal portions of the Mediterranean Salt Giant (MSG) that also occupies the deep, central Mediterranean basins. Although the marine, evaporitic origin of the MSG is undisputed, the analysis of gypsum fluid inclusions and of gypsum-bound water (d18OH2O and dDH2O) suggest that marginal basin gypsum formed from low- to moderate-salinity water masses (5 - 60 ‰), rather than from high-salinity brines (130 - 320 ‰), as expected during the evaporation of seawater.  The formation of low-salinity gypsum poses a fundamental geochemical problem: how can gypsum saturation conditions be met in marginal basins if evaporation does not concentrate marine water to high salinity? In other words, can gypsum saturation be attained by adding Ca2+ and/or SO42- ions rather than by extracting water? We are exploring two geochemical scenarios to explain this phenomenon: (1) the addition of Ca2+ and SO42- to marginal basins by continental runoff, and (2) the non-steady state addition of SO42- to marginal basins via the biogeochemical oxidation of reduced sulfur. Both scenarios may lead - at least theoretically - to the decoupling of saturation state from salinity that is suggested by gypsum geochemical signatures.
High accuracy measurement system for dew and fog water quantification in temperate grassland ecosystems
Authors: Riedl Andreas , Li Yafei , Buchmann Nina , Eugster Werner
Published: March 2020

Dew and fog occur rather frequently in ecosystems all over the world. Still, water from dew and fog is often not considered in ecohydrological budgets. One reason is that there is no reference standard instrument to measure those water inputs into ecosystems. Another reason is that the water input from dew and fog is, compared to the water input from precipitation, a rather small amount at most locations, which makes it difficult to be measured accurately.

We developed a custom-made measurement system for quantifying dew and fog water inputs to temperate grassland ecosystems. The system consists of three high accuracy weighing micro-lysimeters composed of a plant pot which stands on a weighing platform with additional sensors. The weighing micro-lysimeters were designed to quantify even small water gains caused by dew formation on grasses with unprecedented accuracy.  Some former studies on micro-lysimeter design for dew measurements used small-size plant or bare-soil pots in combination with low capacity load cells, which allowed high accuracy measurements, but these systems were not able to mimic natural field conditions in terms of thermal behaviour and plant development. Other studies used large lysimeter systems which were better capable to simulate natural conditions, but required substantial infrastructure for installation and often showing too low accuracy, because of a trade-off between load cell accuracy vs. capacity.

Inside the micro-lysimeter plant pots, we installed soil moisture and temperature sensors to compare thermal and moisture conditions inside the plant pots with sensors installed in a control field plot at 1 m distance. A further component of the measurement system is a visibility sensor which allows to determine if water inputs originate solely from dew or from dew and fog in combination (fog: horizontal visibility < 1000 m). A leaf moisture sensor gives a redundant measurement to sense if leaves are really wet and for how long they stay wet. 

We set up a measuring network with the beforementioned system at eight sites in Switzerland and an additional site in South Tyrol (Italy). The sites were selected to gain representative measurements over an extended elevational gradient (from 500 to 2000 m a.s.l), within areas prone to fog (Swiss Plateau) and rather unlikely fog occurrence (Alps), as well as with low and high precipitation amounts (from 500 up to over 1500 mm/year).

Measuring dew and fog water inputs is expected to be important, as grassland species are able to take up water via foliar water uptake. Thus, dew and fog water can be important water inputs, especially in dry periods during fair weather summer conditions.
Cross-equatorial dry intrusions and their impact on Indian summer monsoon-associated water cycle
Authors: Rai Deepika , Raveh-Rubin Shira
Published: March 2020

Dry intrusion (DI) is the slantwise descent of dry air from the extratropical upper troposphere to the mid/lower troposphere of the lower latitudes. When reaching the tropical regions, DIs substantially change the overall amount of available moisture, ocean surface fluxes into the atmosphere, as well as the atmospheric stability to vertical motion and the 3-dimensional flow and associated dynamics. However, the occurrence of such events has not been quantified systematically. Here, we quantify the climatological occurrence of DIs that extend from the extratropics to tropical regions. Specifically, we focus on events that host subsequent cross-equatorial flow. Using 6-hourly ERA-Interim reanalysis data with a Lagrangian approach, we show that during the summer monsoon season (June to September) DIs enter the tropical region from the southern hemisphere with peaks that exceed 10 % frequency in time. DI arrival into the tropics is associated with dry and cold lower-tropospheric anomalies, and consequently induced ocean evaporation and sensible heat flux into the atmosphere. Although cross-equatorial DIs are rare, a hotspot of such DIs is evident in the Indian Ocean, having a potential role for Indian summer monsoon (ISM) water cycle. The dominance of the ISM for the annual rainfall over India implies that small changes in the evaporation and moisture pathways may influence the ISM precipitation downstream significantly. Indeed, we demonstrate the connection between ISM rainfall and the preceding water-cycle interaction under DI conditions, and further show that DIs entering the Indian subcontinent modify the low-level jets. 
Fault interactions, fault kinematics, and evolution of the structural framework in the Irish Lower Carboniferous
Authors: Torremans Koen , Conneally John , Güven John , Doyle Robert , Guo jiulin , Dunlevy Eoin , Walsh John
Published: March 2020

Fault systems in the Irish Lower Carboniferous are important in relation to its subsurface groundwater, geothermal and mineral resources. For example, major base metal deposits in the world-class Irish Orefield occur in association with normal faults. Despite their economic importance, however, the fault networks and structural framework at depth are still poorly constrained. The Irish Carboniferous Basin is an excellent area to study the extensional fault systems and evolution of rift basins, given the relatively low amounts of later compressional deformation and metamorphism, and because high-quality subsurface datasets exist from several decades of mineral exploration. Our work aimed at developing a coherent structural framework for the Lower Carboniferous in Ireland, to unravel the geometries and kinematics of faulting in a carbonate-dominated rift basin that developed on top of a strong pre-existing structural template in the underlying basement rocks.

We have defined the geometry of key fault systems in the rift across a wide range of scales, using three-dimensional integrated analysis of large datasets. These datasets include public and proprietary onshore 2D reflection seismic, mapping, drillhole, micro-palaeontological, aeromagnetic, electromagnetic, and ground gravity data. Our work has revealed the nature of segmentation patterns and interactions of normal faults, including synthetic and conjugate relay zones. Quantification of fault parameters, kinematic analysis and kinematic restoration have allowed us to gain insights into the distribution of extension during rifting in time and space, using growth sequences and facies changes on faults. The analysis of this structural framework in relation to several mineral deposits, and in combination with lithofacies distribution and the development of bathymetry during basin formation, allows us to better understand current and past fluid flow pathways, especially in relation to base metal mineralising events.
Soil drying and soil structure
Authors: Koestel John
Published: March 2020

Classical soil water retention curves relate tension and water content in soil. Often, the tension is equated with the equivalent diameter of the largest water-filled pores, using the capillary rise equation. This relationship is known to be an approximate one as most soils contain clay minerals that swell and shrink with wetting and drying, respectively. Most notably, cracks are created during drying which may then close again under subsequent wetting. The aim of this study was to investigate how potential soil microbial habitats are influenced under drying. I used three-dimensional X-ray imaging to quantify local volume changes and the associated evolution of the pore-network morphology in 8 undisturbed soil samples (diameter: 67 mm, height 60 mm), sampled at 4 different field sites. In general, cracks formed in all investigated samples. The crack formation corresponded to an increased volume of large pores on the expense of smaller ones. As a result, a larger and better connected macropore network led to an improved aeration of the soil matrix, adding to the increased oxygen supply associated with draining pores. This study demonstrates the large potential of non-invasive imaging methods to advance knowledge on the interaction between soil physics and soil microbiology.
Comparison of the downstream scour to various curvatures of arched groundsill by flume test and computational software
Authors: Yang Fu-Hsuan , Huang Hung-Pin
Published: March 2020

In recent years, the arched groundsill has frequently used to prevent downstream scour and make ecologic habitat in Taiwan. However, the relationship between the depth of downstream scour and curvatures of arched groundsill is still unclear among the specialists and engineers. In order to explore this relationship, this study carried out flume test and calibrated computational software. The result shows that the maximum impact increases with increasing curvatures of both of upward and downward arched groundsills. And, the downstream flow tubes tend to concentration with increasing curvatures of upward arched groundsill while the downstream flow tubes tend to spread uniformly with increasing curvatures of downward one. These phenomena would affect the scale of downstream scour and make the new river geomorphology. Result could be as a reference for choosing convenient curvature when specialists and engineers design arched groundsill.
North Atlantic – European weather regimes in a changing climate: present and future
Authors: Fischer Luise J. , Büeler Dominik , Grams Christian M. , Beyerle Urs , Bresch David N. , Wernli Heini
Published: March 2020

We present findings from an analysis of weather regimes over the North Atlantic and Europe in present and future climate conditions. Weather regimes strongly influence the statistical distribution of surface weather variables. We use a recently developed, all-season North Atlantic - European weather regime classification with seven regimes. These regimes were originally identified in ERA-Interim reanalyses and, in this study, we investigate how they are represented in climate simulations using the CESM1 large ensemble for present-day and future (RCP8.5) climate conditions. With these regimes, the classification of the flow conditions in the considered region goes beyond the classical categorization according to the North Atlantic oscillation index; the weather regimes explicitly capture different flavors of strong zonal flows and the occurrence of blocking over Greenland, Scandinavia, and Central Europe, respectively. In ERA-Interim they explain 70% of the variability in geopotential height at 500 hPa year-round. Our analysis quantifies how well CESM1 represents the statistics of the weather regimes in present-day climate and how strongly their frequencies change in the future climate scenario. In addition, we identify statistical relationships between weather regimes and their resulting impacts on spatial patterns of surface variables such as precipitation. We compare those patterns and characteristics of the weather regimes identified in ERA-Interim to their characteristics in simulations of present and future climate conditions.

This analysis leads to insight into the representation of and changes in atmospheric circulation in one particular climate model, and, at the same time, it quantifies how well the climate model captures the observed link between surface weather and weather regimes. This approach contributes to improving our understanding of atmospheric circulation changes and their impact on a regional scale, and it may benefit the interpretation and communication of climate projections.
Estimates of seismo-acoustic transfer functions relevant to CTBT IMS T-phase stations
Authors: Nielsen Peter , Zampolli Mario , Le Bras Ronan , Haralabus Georgios , Stevens Jeffry , Hanson Jeffrey
Published: March 2020

The Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System (IMS) is a world-wide network of stations and laboratories designed to detect nuclear explosions underground, in the oceans and in the atmosphere. The IMS incorporates four technologies: seismic, hydroacoustic and infrasound (collectively referred to as waveform technologies), and radionuclide (particulate and noble gas). The focus of this presentation is the hydroacoustic component of the IMS, which consists of 6 hydroacoustic stations employing hydrophones deployed in the oceans and 5 near-shore seismic stations, called T-phase stations, located on islands or continental coastal regions. The purpose of T-phase stations is to detect water-borne hydroacoustic pressure waves converted into seismic waves that propagate on the earth’s crust and are detected by land seismometers. However, the conversion process from in-water pressure to near-interface seismic waves is complex and strongly dependent on the properties of the local underwater and geological environment. To further understand this conversion process, state-of-the-art hybrid seismo-acoustic wave propagation models have been applied to simplified environments and to scenarios representative of the conditions encountered at IMS T-phase stations to compute broadband pressure time-series in the water and particle  velocity components on-land. Transfer functions from in-water pressure to on-land seismic particle velocity and vice versa were estimated both from modelling results and from real data acquired in locations where the hydrophones and (non-IMS) seismic stations were within 50-km distance. The presented results have been used to give a first assessment of the feasibility of characterizing the hydroacoustic phase of an in-water event by on-land seismic recordings at IMS T-phase stations, subject to limited a-priori environmental information and limiting factors, such as band-width and instrumental and/or environmental noise.
State tagging for improved earth and environmental data quality assurance
Authors: Tso Michael , Henrys Peter , Rennie Susannah , Watkins John
Published: March 2020

Long-term monitoring data that considers a wide array of environmental variables provides key insights to environmental change because responses of ecosystem functions and services to environmental drivers are inherently long-term and strongly interlinked. To ensure that the data are reliable for analysis and interpretation, they must undergo quality assurance procedures. However, the expected or acceptable range of data values vary greatly as the state of the ecosystem changes. Current quality assurance procedures for environmental data take no consideration of the system state at which each measurement is made, and provide the user with little contextual information on the probable cause for a measurement to be flagged out of range. We propose the use of data science techniques to tag each measurement with an identified system state. The term “state” here is defined loosely and they are identified using k-means clustering, an unsupervised machine learning method. The meaning of the states is open to specialist interpretation. Once the states are identified, state-dependent prediction intervals can be calculated for each observational variable. This approach provides the user with more contextual information to resolve out-of-range flags and derive prediction intervals for observational variables that considers the changes in system states. Our highly flexible and efficient approach is applicable to any point data time series in earth and environmental sciences, regardless of their sub-discipline. Such advantage is particularly relevant when conducting simultaneous analysis of multiple processes and feedbacks, where a wide variety of data is used.

We illustrate our approach using the moth and butterfly data from the UK Environmental Change Network (ECN), where meteorological variables are used to define system states. A web application is publicly available to allow users to explore the method on various ECN site, while a generic is also available for users to upload their own data files. Our work contributes to the ongoing development of a better data science framework that allows researchers and other stakeholders to find and use the data they need more readily and reliably.

 
Documentation of climate change data supporting cross-domain data reuse
Authors: Stockhause Martina , Greenslade Mark , Hassell David , Pascoe Charlotte
Published: March 2020

Climate change data and information is among those of the highest interest for cross-domain researchers, policy makers and the general public. Serving climate projection data to these diverse users requires detailed and accessible documentation.

Thus, the CMIP6 (Coupled Model Intercomparison Project Phase 6) data infrastructure consists not only of the ESGF (Earth System Grid Federation) as the data dissemination component but additionally of ES-DOC (Earth System Documentation) and the Citation Service for describing the provenance of the data. These services provide further information on the data creation process (experiments, models, …) and data reuse (data references and licenses) and connect the data to other external resources like research papers.

The contribution will present documentation of the climate change workflow around the furtherInfoURL page serving as an entry point. The challenges are to collect quality-controlled information from the international research community in different infrastructure components and to display them seamlessly alongside on the furtherInfoURL page.

 

References / Links:

CMIP6: https://pcmdi.llnl.gov/CMIP6/

ES-DOC: https://es-doc.org/

Citation Service: http://cmip6cite.wdc-climate.de
Major controls of base flow soluble reactive phosphorus losses in humid temperate headwater streams
Authors: Rode Michael , Dupas Remi
Published: March 2020

Long-term Soluble Reactive Phosphorus (SRP) monitoring in headwater streams in central Europe revealed a seasonal pattern of SRP concentrations during low flow periods, with highest concentrations in summer and lowest in winter. These seasonal concentration amplitudes often exceed the eutrophication threshold during the summer eutrophication-sensitive period. It is assumed that temperature dependent biogeochemical processes control the underlying P release mechanism, where redox processes may be responsible for this increase. Several studies have highlighted the crucial role of reactive zones such as riparian wetlands in controlling solute export regimes. Moreover especially in forest headwater streams, in-stream assimilatory uptake shows a distinct seasonal behaviour because of varying shading conditions. This can also lead to seasonal SRP amplitudes. Furthermore sorption and desorption processes are temperature dependent which may alter in-stream SRP release during the year.

Often SRP concentrations are higher in agricultural streams than in more pristine headwaters. It is not clear how land use (e.g. P status of soils) may impact the baseline SRP concentrations and which factors control the seasonal change in SRP stream concentration (riparian groundwater heads and redox processes, temperature, in-stream release and uptake processes). Therefore the objective of this study is to disentangle land use impacts from hydrological and biogeochemical controls of low flow SRP losses.  A comparative study on seasonal SRP concentration patterns will be presented comprising around 53 long term monitored headwater catchments in humid temperate climate of northern Europe and the United States. Based on hydrological and SRP headwater signals and catchment properties, P release processes are discussed. The results of the study will allow to target SRP mitigation strategies based on knowledge of the dominating control of SRP loss from headwater streams. 
Factors influencing the boundary layer height and their relationship with air quality in the Sichuan Basin, China
Authors: Cao Bangjun
Published: March 2020

We investigated the factors influencing the daily maximum boundary layer height (hmax) and their relationship with air quality in the Sichuan Basin, China. We analyzed the factors influencing hmax on cloudy and sunny days in winter using five years of observational data and a reanalysis dataset and investigated the relationship between hmax and air quality. The inversion layer in the lower troposphere has a critical impact on hmax on cloudy days. By contrast, the sensible heat flux and wind shear are the main influencing factors on sunny days, although the contribution of the sensible heat flux to hmax is less than that of the wind shear. This is because the turbulence is mainly affected by mechanical mixing induced by the topographic effect of the Tibetan Plateau to the west of the Sichuan Basin. The secondary circulation over the Sichuan Basin is weaker on cloudy days than on sunny days. These results are important for understanding the dispersion of air pollutants over the Sichuan Basin.
Cross-Slope Observations in the Bellingshausen Sea, Southern Ocean
Authors: Oelerich Ria , Heywood Karen J. , Damerell Gillian M. , Thompson Andrew F.
Published: March 2020

The Bellingshausen Sea, located between the West Antarctic Peninsula and the Amundsen Sea, is poorly observed, compared with its neighbours. The Antarctic Slope Front (ASF), that rings the continental slope of Antarctica, supports a westward current (the Antarctic Slope Current). The structure and variability of this current affect exchange processes close to Antarctica such as the transport of warm Circumpolar Deep Water onto the Antarctic continental shelf. This water mass is responsible for the transport of heat across the shelf and therefore the basal melting of ice shelves. Due to the lack of observations, it is still unclear if the ASF even exists in the Bellingshausen Sea or if there are other processes moderating the transport of warm water onto the shelf.

We present ship-based and glider-based CTD data collected in 2007 and 2019, which in total provide 7 cross-slope sections in the Bellingshausen Sea. Geostrophic velocities are referenced to lowered ADCP data, shipboard ADCP data and the Dive Average Current. Cumulative transports show remarkable differences between the years 2007 and 2019. The sections of 2007 provide cumulative transports of up to 3.5 Sv eastward. In contrast, the sections in 2019 have cumulative transports up to 2 Sv westward. The sections from 2007 and 2019 are in very similar locations, indicating a temporal change rather than a spatial change.

We compare the cross-slope sections from the observations with sections from the NEMO 1/12 ° model output. A time series of cumulative transports from the model, covering the years from 2000 to 2010, allows us to identify seasonality and interannual variability in this current system.
Machine Learning Rain Formation and the Impacts on Clouds, Precipitation and Radiation
Authors: Gettelman Andrew , Chen Chih-chieh , Gagne David
Published: March 2020

Cloud, aerosols and precipitation processes are perhaps the most critical uncertainties for weather and climate prediction. The complex nature of sub grid scale clouds makes traceable simulation of clouds and precipitation across scales difficult (or impossible). However, many observations and detailed simulations of clouds are available as input to larger scale models. Machine learning provides another potential tool to improve our empirical parameterizations of clouds. Here we present a comprehensive investigation of replacing the warm rain formation process in an earth system model with emulators that use detailed treatments from small scale and idealized models: specifically a stochastic collection kernel and a superdroplet approach. The emulators consist of multiple neural networks that predict whether specific tendencies will be nonzero and the magnitude of the nonzero tendencies. We describe the opportunity (massive speed up of cloud process calculations) and the risks of overfitting, extrapolation and linearization of a non-linear problem by using perfect model experiments with and without the emulators. The impacts on short term time tendencies of clouds and precipitation, as well as long term climatological means and important emergent properties of the climate system (like radiative forcing through aerosol-cloud interactions and cloud feedbacks to climate change) are assessed. 
Modelling the production of terrestrial gamma-ray flashes during the final leader step
Authors: Köhn Christoph , Chanrion Olivier , Matthias Heumesser , Dimitriadou Krystallia , Neubert Torsten
Published: March 2020

Recent measurements by the Atmosphere-Space Interactions Monitor (ASIM) indicate that the production of energetic electrons and of subsequent terrestrial gamma-ray flashes (TGFs) occurs immediately prior to intracloud lightning breakdown. Inspired by this finding, we relate the production of high-energy particles to the occurrence of streamer coronas initiated during the final leader step when the leader is in the vicinity of the upper cloud charge layer. Therefore, we model the acceleration of electrons and the subsequent production of energetic photons in the electric fields of the two encountering streamer coronas which are initiated in the vicinity of the leader tip and of the charge layer. Applying a particle Monte Carlo code, we first initiate thermal electrons in the electric field of the leader tip and subsequently turn on the streamer coronas and simulate the acceleration of electrons from thermal energies to energies of several tens of MeV. We present the temporal evolution of the electron and photon energies and spectra, and discuss the role of the electric fields of the encountering streamer coronas. Finally, we relate our results to ASIM measurements and discuss the duration and the relative timing of TGF bursts.
Debris flow monitoring in China
Authors: Guo Xiaojun
Published: March 2020

Abstract: Debris flow monitoring provides valuable data for scitienfic research and early warning, however, it is of difficulty to sucessfully achive because of the great damage of debris flows and the high cost. This report introduces monitoring systems in two debris flow watersheds in western China, the Jiangjia gully (JJG) in Yunnan Province and the Ergou valley in Sichuan Province. JJG is loacted in the dry-hot valley of Jinsha River, and the derbis flows are frequent due to the semi-arid climate, deep-cut topography and highly weathered slope surface. A long-term mornitoring work has been conducted in JJG and more than 500 debris flows events has been recorded since 1965. The monitoring system consists of 10 rainfall gauges and a measuring section, with instruments to measure the flow depth and velocity; and flow density is measured through sampling the fresh debris flow body. Ergou lies in the Wenchuan earthquake affected area and the monitoring began in 2013 to investigate the characteristics and development tendency of post-earthquake debris flows. Three stations were set up in the mainstream and tributaries, with instruments to measure the flow depth, velocity, and density. Over 10 debris flow events were recorded up to date.

Based on the monitoring output, the rainfall spatial distribution and thresholds for debris flows are proposed. The debris flow dynamics characteristics are analyzed, and the relations between the parameters, e.g. density, velocity, discharge and grain compositions are presented. The debris flow formation modes and the mechanisms in different regions are discriminated and simulation methods are suggested. It is anticipated that the monitoring results will promote understanding of debris flow characteristics in the western China.

Keywords: Debris flow, monitoring, rainfall, discharge, formation. 
Extreme sensitivity and climate tipping points
Authors: von der Heydt Anna , Ashwin Peter
Published: March 2020

The equilibrium climate sensitivity (ECS) is widely used as a measure for possible future global warming. It has been determined from a wide range of climate models, observations and palaeoclimate records, however, it still remains relatively unconstrained. In particular, large values of warming as a consequence of atmospheric greenhouse gas increase cannot be excluded, with some of the most recent state-of-the-art climate models (CMIP6) supporting (much) more warming than previous generations of climate models. Moreover, a number of tipping elements have been identified within the climate system, some of which may affect the global mean temperature. Therefore, it is interesting to explore how the climate systems response (e.g. ECS) behaves when the system is close to a tipping point. 
A climate state close to a tipping point will have a degenerate linear response to perturbations, which can be associated with extreme values of the equilibrium climate sensitivity (ECS). In this talk we contrast linearized ('instantaneous') with fully nonlinear geometric ('two-point') notions of ECS, in both presence and absence of tipping points. For a stochastic energy balance model of the global mean surface temperature with two stable regimes, we confirm that tipping events cause the appearance of extremes in both notions of ECS. Moreover, multiple regimes with different mean sensitivities are visible in the two-point ECS. We confirm some of our findings in a physics-based multi-box model of the climate system.

Reference
P. Ashwin and A. S. von der Heydt (2019), Extreme Sensitivity and Climate Tipping Points, J. Stat. Phys.  370, 1166–24. http://doi.org/10.1007/s10955-019-02425-x.
Lake Tsunamis: Causes, Consequences and Hazard investigated in a multidisciplinary project
Authors: Kremer Katrina , Anselmetti Flavio S. , Bacigaluppi Paola , Boes Robert M. , Evers Frederic M. , Fäh Donat , Fuchs Helge , Hilbe Michael , Kopf Achim , Lontsi Agostiny M. , Nigg Valentin , Shynkarenko Anastasiia , Stegmann Sylvia , Strupler Michael , Vetsch David F. , Wiemer Stefan
Published: March 2020

Tsunamis can occur in lacustrine environments, similar to marine settings. In lake settings, these tsunamis are mainly generated by mass-movement processes displacing large volumes of water, and triggered by seismic or aseismic phenomena. In Swiss lakes, several historical tsunamis are reported. Some of the most prominent examples are: the 563 AD Lake Geneva tsunami presumably caused by a rockfall-induced delta failure, the 1601 AD Lake Lucerne tsunami caused by earthquake-triggered sublacustrine mass movements, and the 1687 AD Lake Lucerne tsunami that was caused by a delta failure.

 

Nowadays, the shorelines of many Swiss lakes are densely populated and host important infrastructures. The occurrence of lake tsunamis in Switzerland is known, however, we still miss a workflow to assess the hazard related to tsunamis. Within the framework of a multidisciplinary project (Lake Tsunamis: Causes, Consequences and Hazard), funded by the Swiss National Science Foundation and the Federal Office for the Environment, we aim towards better understanding lake-tsunami processes using Swiss lakes as laboratories.

 

The major objectives of this project are to investigate a) the diverse causes of lake tsunamis, b) the geotechnical and sedimentological properties of unstable slope sediment, c) the potentially unstable sediment volumes on charged slopes, d) the wave generation, propagation and shore run-up, e) the onshore and shallow offshore tsunami deposits and d) their related hazard.

 

Since 2018, extensive field work using ocean bottom seismometers and cone penetration tests, as well as laboratory tests on sediment sample have been performed to assess the slope stability during seismic shaking on Lake Lucerne. Tsunami waves have been reproduced at laboratory scale to benchmark the numerical simulations of generation, propagation and run-up of tsunamis in lakes. To characterize and date historical and prehistorical tsunami deposits, on and off-shore sediment cores have been retrieved at Lake Lucerne, Geneva, Zurich and Sils. A first work-flow to assess the tsunami hazard related to earthquake-triggered sublacustrine mass movements is proposed. In this contribution, we will summarise the current status of this project.