bluuebunny/crossref_metadata_2025 huggingface dataset:
The Urban Biocide Terbutryn: Field investigations to explore release and reactive transport under environmental conditions
Authors: Junginger Tobias , Payraudeau Sylvain , Imfeld Gwenaël
Published: March 2022

Urban biocides like terbutryn are used in construction materials such as render and paints on façades to prevent the growth of algae and fungi. With wind-driven rain, those contaminants leach into the environment and pose a risk for groundwater contamination. In our study, we combined leaching experiments with artificial facades to quantify biocide release, lysimeter experiments to get insights into the reactive transport under environmental conditions, and field sampling in an urban catchment to follow-up biocide release from source (building facades) to sinks (stormwater retention systems/ groundwater). We use concentrations of terbutryn as well as its four major transformation products to establish mass balances. Furthermore, we use Compound-Specific Isotope Analysis (CSIA) as a concentration-independent tool to identify the dominant degradation processes in the environment by taking into account (i) isotopic enrichment of stable isotopes by dual-isotope plots and (ii) patterns of formed transformation products. Façade leaching experiments show that high quantities of terbutryn remain on the facades and leaching continues for a long period. Transformation products are already formed on the facades through photodegradation. Reactive transport on typical urban surfaces (gravel, paved stones with joints, soil) indicates high retention of terbutryn in the grass lysimeter and faster leaching in gravel and pavement lysimeters with low recoveries of terbutryn in the first 2 months (3 %, 1 % and <1 % in gravel, paved and grass lysimeter, respectively). In all lysimeters, transformation products were formed, exceeding the concentrations of leached terbutryn at some sampling points, indicating higher mobility through better solubility in water of the daughter compounds. The overall extend of (bio-)degradation in the lysimeters was low for terbutryn, as supported by CSIA data (changes in Δδ13C < 2‰). Grab samples in a stormwater retention pond and swale system in an urban catchment confirmed the leaching of terbutryn and transformation products in a catchment from 6-year-old buildings with concentrations of terbutryn between 3 and 70 ng/L, as well as TP terbutryn sulfoxide, exceeding 400 ng/L. Our study implies the importance of detailed monitoring of urban biocides to understand the reactive transport processes on their pathways into groundwater and underlines the importance of monitoring also transformation products in typical monitoring schemes.
Different mechanical behavior at the same P-T conditions in biotite-quartz assemblage: interconnectivity and composition effect of experimentally deformed mica
Authors: Alaoui Khadija , Airaghi Laura , Stünitz Holger , Raimbourg Hugues , Précigout Jacques
Published: March 2022

The effect of composition on microstructural development and mechanical strength was tested using mica-quartz-aggregates during deformation experiments.

This study used two chemically different biotite minerals mixed with quartz: (1) high F-phlogopite and (2) intermediate biotite in order to investigate the role of biotite-bearing systems for the development of shear zones and strain accommodation. Shear experiments (Griggs-type apparatus) were performed using mica (30 vol. %) and quartz (70 vol. %) assemblages at 750 and 800°C, 1000 MPa and a shear strain rate of ~10-5 s-1.

Mechanical results for the F-phlogopite-bearing assemblage indicate strong samples, approximately equivalent to pure quartz samples (Richter et al., 2018), deforming at differential stresses of 764-1097 MPa). F-phlogopite flakes are preferentially oriented parallel to the main shear direction, but poorly interconnected. Most of the strain is accommodated by quartz behaving as an interconnected network. Cathodoluminescence imaging reveals that quartz recrystallizes mainly by local pressure-solution and its strength controls the overall strain accommodation.

In contrast, intermediate biotite assemblages are significantly weaker and deform for lower differential stresses of 290-327 MPa, as expected for natural rocks. Biotite flakes form an interconnected network accommodating most of strain.

The interconnectivity of biotite grains thus plays a major role in weakening quartz-biotite assemblages. However, at similar P-T-strain and grain size conditions, the capacity of biotite grains to interconnect may also depend on its chemical composition, particularly considering the effect of trace elements incorporation (as fluorine) on the strength of the biotite interlayer bounds (Dahl et al., 1996, Figowy et al., 2021). This led us to conclude that different types of mica, behaving differently, strongly affect strength, deformation mechanism, and microstructure of the rock due to their structure, composition and stability fields.
TAO data support the existence of large amplitude wind-driven high frequency variations in the cross-equatorial overturning circulation
Authors: Blaker Adam , Baker Lois , Bell Mike , Hirschi Joel
Published: March 2022

Large amplitude oscillations in the meridional overturning circulation (MOC) have been found near the equator in all major ocean basins in the NEMO ocean general circulation model. With periods of 3-15 days and amplitudes of ~±100 Sv in the Pacific, these oscillations have been shown to correspond to zonally integrated equatorially trapped waves forced by winds within 10° N/S of the equator, and can be well reproduced by idealized wind-driven simulations linearized about a state of rest. Observations of dynamic height from the Tropical Atmosphere Ocean (TAO) mooring array in the equatorial Pacific also exhibit spectral peaks consistent with the dispersion relation for equatorially trapped waves. Here, we revisit the TAO observations to confirm that the amplitude of the oscillations is consistent with the simulations, supporting the modelled large amplitude MOC oscillations. We also show that the zonal structure of the frequency spectrum in both observations and simulations is predicted by changes in the baroclinic wave speed with variation in stratification across the ocean basin.
Who presented and convened at EGU General Assemblies 2015-2021?
Authors: Stadmark Johanna , Beniest Anouk , Alves de Jesus-Rydin Claudia
Published: March 2022

The first step for institutions committed to equality, diversity and inclusion is to know their demographics. This presentation includes descriptive statistics for 7 consecutive years (2015–2021) based on presentations and convenorship at the EGU General Assemblies.

In the years 2015-2019, when the meeting was a physical meeting in Vienna, around 90% of the participants gave presentations. In 2020 the meeting was held online at short notice and the registration for participation was free of charge. In 2021 the entire meeting was planned online already at the time of submission of abstracts and the participant fee was lower than for the previous physical meetings. We cannot completely compare the participant data from the online meetings with the previous years, therefore this presentation will focus on the gender, career stage, and geographical distribution among presenters and convenors.

The total number of presenters has increased over the time period 2015-2021, and this increase was observed throughout all career stages. The proportion of women presenters have increased from 32% in 2015 to 39% in 2021, with a leap from 36 to 39% between 2020 and 2021. A similar trend was observed for the convenors, an increase in total numbers over the years and a higher proportion (39%) of women in 2021 than in 2015 (26%). This trend of increasing numbers of conveners was observed independent of career stage until 2018. Since then, the number of senior scientist conveners increased, whereas the number of Early Career Scientist conveners has dropped to a number lower than 2015. The gender difference between “presenters per convenors”-ratio has been shrinking since 2015 and was similar for women and men in 2021.

Since EGU General Assembly is the largest geosciences conference in Europe and still growing, understanding the demographic evolution and their participation to EGU activities, including the GA, of various groups is an important tool for EGU governing body to draw targeted actions to ensure that the current procedures are fair and that all in the community are being and feeling included. We therefore aim to analyse the changes in demographics with regards to gender, career stage as well as to geographical distribution of the presenters and convenors also in coming years to better understand the potential impacts of meetings organized online or physically, or as a combination of both these modes. 
Do salinity variations along the East Greenland shelf show imprints of increasing meltwater runoff? 
Authors: Schiller-Weiss Ilana , Martin Torge , Biastoch Arne , Karstensen Johannes
Published: March 2022

Accelerated melting of the Greenland Ice Sheet is considered to become a tipping point in the freshwater balance of the subpolar North Atlantic (SPNA). The ramifications of increased freshwater input have been projected to reduce deep convection in neighboring Labrador and Irminger Seas. The East Greenland Current is a primary pathway for transporting Arctic-sourced freshwater and Greenland glacial meltwater into the SPNA. Understanding the variability of the East Greenland (Coastal) Current (EGC/EGCC) is of high importance, as it contains the first imprint of ice melt which flows directly into the current when entering the open ocean. 

We performed a cross sectional analysis of salinity and temperature along the eastern Greenland shelf using output from an eddy-rich (1/20o) ocean model (VIKING20X), which is forced with time-varying Greenland freshwater fluxes (Bamber et al., 2018), and the observational-based reanalysis product (GLORYS12V1 [1/12o]) from 1993 to 2019. A time varying mask referenced to a salinity threshold of ≤ 34.8 psu was used to isolate the EGC close to the shelf at five locations for both winter (JFM) and summer (JAS) months. Selected locations are major ocean gateways, glacier outlets/fjords, and observing arrays: Fram Strait, Denmark Strait, just south of 66oN (Helheim/~Sermilik) and 63.5oN (Bernstorff), and OSNAP East extending up to the central Irminger Sea. Export of polar water from the Arctic Ocean through Fram Strait sets the initial, low salinity signature in the EGC, which mixes with Atlantic water further downstream and increases in salinity. However, in our simulation, we find lower salinity values again south of Denmark Strait in summer with some notable fresh imprints of extreme meltwater runoff in individual years, such as 2010 and 2012. Furthermore, we observe that for all the cross sections, excluding Fram Strait, there is a negative trend in salinity from 1993 to 2010 followed by a decade in which the salinity trend at Denmark Strait and further south decouples from that in Fram Strait in winter and summer. We explore the reasons for the temporal variations in salinity (and temperature) along the East Greenland Shelf and the potential of different data products to show early imprints of enhanced meltwater runoff into the EGC.
Signatures of midlatitude heat waves in the global atmospheric circulation 
Authors: Strigunova Iana , Blender Richard , Lunkeit Frank , Žagar Nedjeljka
Published: March 2022

This work investigates systematic changes of the global atmospheric circulation during midlatitude heat waves in spectral space. The basis functions for the expansion of global data are the eigensolutions of the linearised primitive equations; here, the Rossby waves are represented in terms of Hough harmonics that are defined by their zonal wavenumber, meridional modes and vertical structure functions. Their orthogonality allows diagnostics in terms of energy of the zonal mean flow and wave energies.  The diagnostic provides a holistic dynamical picture of the variability spectrum of Rossby waves and allows scale-selective filtering of modes of variability in physical space.  The method is applied to reanalysis datasets starting in 1980. 

The reconstructed circulation (the inverse projection onto wind and geopotential  fields based on selective filtering) during heat waves is dominated by large-scale anticyclonic systems in agreement with previous studies, thereby demonstrating the physical meaningfulness of the applied method. Probability distribution functions of Rossby wave energies are evaluated separately for the zonal mean flow, for the planetary and synoptic zonal wavenumbers with  the  tropospheric barotropic structure. Time series of wave energies are characterised by a chi-square distribution.  The chi-square skewness shows a reduction in the number of involved degrees of freedom for planetary-scale circulation by 50%  during the heat waves. This reduction yields a quantitative estimate for the coarse large-scale structure of blocking events and its barotropic  structure in the midlatitude troposphere.  The robustness of the results is ensured by considering the four reanalyses: ERA5, ERA-Interim, JRA-55 and MERRA datasets. 
Basal hydrofractures near sticky patches
Authors: Zhang Hanwen , Davis Timothy , Katz Richard , Stevens Laura , May Dave
Published: March 2022

Basal crevasses are macroscopic structural discontinuities at the base of ice sheets and glaciers. Sticky patches (also referred to as sticky spots) are regions of high basal shear stress caused by low subglacial water pressure or topographic high of the bedrock. Motivated by observations, we hypothesise that in the presence of basal water pressure, spatial variations in basal shear stress on the sticky patches can promote and localise basal crevassing. In the theoretical context of linear elastic fracture mechanics, we develop a model evaluating the effect of shear stress variation on the growth of basal crevasses, finding that the existence of sticky patches can promote mixed-mode basal crevassing on the downstream end. By simulating the quasi-static growth of such mixed-mode basal crevasses, we find that such crevasses tend to incline upstream and propagate along a specific path, which can be approximated by the principal stress trajectories in the uncracked ice. A detailed exploration on the dimensionless parameter space indicates that the crevassing is controlled by three parameters—the flotation fraction, the relative magnitude of excess shear stress, and the relative size of the sticky patch. Inspired by the crevassing in the elastic model, we also explore the propagation of basal crevasses using the viscoelastic rheology.
The 29th November, 2020 Earthquake in the Eastern Cordillera (NW Argentina): new results on InSAR and coherence time-series analyses
Authors: Viotto Sofia , Bookhagen Bodo , Toyos Guillermo , Torrusio Sandra
Published: March 2022

On November 29, 2020 an ~6 Mw earthquake occurred at a depth of almost 10 km (United States Geological Survey) in the Eastern Cordillera in northwestern Argentina. The epicenter was located near the towns of Caspalá and Santa Ana (Salta province) in the Quebrada de Humahuaca, and the maximum surface deformation was measured over the Hornocal syncline. The earthquake was the first recorded in this area in the last three decades. As a consequence, several mass movements were triggered from the nearby slopes composed of mechanically weakened rocks. Fortunately, only damage to buildings and infrastructure were reported.

This research presents the vertical deformation associated with this event relying on Sentinel 1A/1B C-band and ALOS2 L-band data. We generate interferometric time series from the Sentinel data, spanning 2 years prior to the event, on ascending and descending passes and invert to displacement time series. We use ALOS2 (Scansar mode) data on ascending and descending passes, and create interferograms by pairing images acquired before and after the earthquake. We determine the three-dimensional motion components by combining the four view angles. Using the Sentinel-1 data, we analyzed the coherence time series to identify mass movements triggered by the earthquake, thus we present a mass-movement detection approach for SAR coherence data using varying time scales and durations of coherence calculations.

Based on the interferometric time series from the Sentinel data on ascending and descending passes, we measured a maximum cumulative line-of-sight (LOS) displacement of about 10 cm over the Hornocal syncline. We measured similar LOS displacement in interferograms based on ALOS data. We determine that the Hornocal fold subsided and the maximum deformation area was constrained between 65.25° and 65.10° W longitude with 23.31° S as central latitude. Moreover, results based on the coherence time series showed that the maximum concentration of mass movements occurred within the closest 10 km of the epicentre, mainly on the slopes of the Hornocal syncline. Additional mass movement signals were recorded several kilometres from the source. The mass movements triggered by the earthquake exceed the number of mass movements associated with rainfall during the South American Monsoon.
Identification and separation of infrasound signals from storms and quarry blasts via machine learning algorithms
Authors: Pásztor Marcell , Bondár István
Published: March 2022

The infrasound array in Hungary has been operational since May 2017 at Piszkés-tető. Since then, it has collected over a million PMCC detections from various known sources such as microbaroms from the Northern Atlantic, quarry blasts and mine explosions, eruptions of Etna, storms, airplanes and so on. The goal of this study is to train, test, validate and compare machine learning models such as Random Forest and Support Vector Machine, for identification and separation of infrasound signals from storms and quarry blasts. The dataset contains identified signals from previous studies and from the Hungarian Seismo-Acoustic Bulletins. The features for training are extracted both from the time and frequency domains of the signals.
WRF Simulations on the Impacts and Responses of Extreme Weather Events: From the Perspectives of Climate Change and Urbanisation over UK Cities
Authors: Du Sichan , Zhuo Lu , Kendon Elizabeth J. , Han Dawei , Liu Ying , Wang Jiao , Wang Qin
Published: March 2022

In the twenty-first century, extreme weather events leading to flooding and heat waves, have become one of the most severe challenges in urban areas, especially under the circumstances of local climate change and rapid urbanisation. In the future, cities are going to encounter more severe natural disaster risks and understanding how these could combine with modification of the urban environment (for example through adoption of green infrastructure) is critical for decisions relating to mitigation and adaptation to climate change. Green infrastructure is a subset of resilient infrastructure, which may mitigate the adverse effects caused by extreme weather and contribute to regulating urban climate. In addition, high-performing green spaces bring additional benefits for society in terms of health and wellbeing. The Weather Research and Forecasting (WRF) model is a numerical weather prediction system supporting both atmospheric research and operational forecasting. Within this modelling system, there is the possibility to modify parameters according to various urban areas within the WRF-Urban configuration. In this study, Newcastle upon Tyne (a UK city with the benefit of a lot of observational sensor data) is selected as an initial target city for identifying the optimal WRF configuration by varying the model resolution, domain size and nesting strategy. Future work will explore the influence of implementing green infrastructure in the context of climate change and urbanisation, then extending this analysis to London.
The associations between environmental factors and COVID-19: early evidence from China
Authors: Meng Xia , Yao Ye , Wang Weibing , Kan Haidong
Published: March 2022

The Coronavirus (COVID-19) epidemic, which was first reported in December 2019 in Wuhan, China, has been becoming one of the most important public health issues worldwide. Previous studies have shown the importance of weather variables and air pollution in the transmission or prognosis of infectious diseases, including, but not limited to, influenza and severe acute respiratory syndrome (SARS). In the early stage of the COVID-19 epidemic, there was intense debate and inconsistent results on whether environmental factors were associated with the spread and prognosis of COVID-19. Therefore, our team conducted a series studies to explore the associations between atmospheric parameters (temperature, humidity, UV radiation, particulate matters and nitrogen dioxygen) and the COVID-19 (transmission ability and prognosis) at the early stage of the COVID-19 epidemic with data in early 2020 in China and worldwide. Our results showed that meteorological conditions (temperature, humidity and UV radiation) had no significant associations with cumulative incidence rate or R0 of COVID-19 based on data from 224 Chinese cities, or based on data of 202 locations of 8 countries before March 9, 2020, suggesting that the spread ability of COVID-19 among public population would not significantly change with increasing temperature or UV radiation or changes of humidity. Moreover, we found that particulate matter pollution significantly associated with case fatality rate (CFR) of COVID-19 in 49 Chinese cities based on data before April 12, 2020, indicating that air pollution might exacerbate negative prognosis of COVID-19. Our studies provided an environmental perspective for the prevention and treatment of COVID-19.
Geothermal potential of small sub-volcanic intrusions in a typical Icelandic caldera setting
Authors: Burchardt Steffi , Bazargan Mohsen , Bessi Gestsson Einar , Ronchin Erika , Tuffen Hugh , Heap Michael J. , Davidson Jonathan , Kennedy Ben , Hobé Alex , Hieronymus Christoph , Saubin Elodie
Published: March 2022

Geothermal exploration targets large magmatic intrusions as heat sources because of their size, longevity, and amount of stored energy, but as shallow volcanic plumbing systems comprise numerous smaller intrusions, their geothermal potential warrants consideration. Here, we evaluate the geothermal impact of dykes and sills on caldera-infill rocks. We present geological data and geothermometry on intrusions in the eroded Breiðuvík caldera in Northeast Iceland, which serves as an analogue to the active, and geothermally exploited, Krafla volcano. This data informs 2D finite element models of dyke and sill intrusions that consider heat transfer in porous media. Our results indicate small intrusions create considerable thermal anomalies in their immediate vicinity. These anomalies are larger-magnitude and longer-lasting for individual thick sills and dykes, but networks of smaller sills and dykes emplaced close in time and space can create more widespread thermal anomalies that may be viable economic targets for decades after their emplacement.
Multi-decadal and centennial modes of AMOC variability and their dependence on mean state in a climate model
Authors: Fedorov Alexey , Ferster Brady , Mignot Juliette , Guilyardi Eric
Published: March 2022

Climate models exhibit large differences in the mean state and variability of the Atlantic meridional overturning circulation (AMOC), including in AMOC strength and the characteristic amplitude and frequency of its variability. Across different GCMs, AMOC long-term variability ranges from decadal to multi-centennial and its magnitude from a fraction of to several Sverdrups (Sv). In this study, we conduct ensemble experiments, using the latest coupled model from Institut Pierre Simon Laplace (IPSL-CM6A-LR), to investigate systematically how AMOC variability depends on the AMOC mean state. In the control simulations of this model AMOC mean volume transport is about 12Sv, while AMOC variability is dominated by two distinct modes – a multi-decadal mode with periodicity between 20-30 years and a centennial mode with periods of 100-200 years. The former mode is weaker and driven by temperature variations, while the latter is stronger and driven by salinity anomalies. To modify the mean state of the AMOC in the model we use an indirect method based on robust atmospheric teleconnections from the tropical Indian ocean (TIO) to the Atlantic as described in two recent studies (Hu and Fedorov, 2019; Ferster et al., 2021). Both studies have shown that warming the TIO results in an increased AMOC strength, while cooling the TIO results in a weakened AMOC. To change the Indian ocean temperature in our perturbation experiments we nudge TIO SST by -2°C, -1°C, +1°C, and +2°C; and the experiments last for approximately 1000 years. This allows us to go from a nearly collapsed AMOC state below 3Sv to a more realistic mean state of about 16Sv. We find that both modes of AMOC variability persist throughout the experiments while their amplitude increases almost linearly with AMOC mean strength, yielding linear relationships between the amplitude of variability (standard deviation) and AMOC mean strength of +0.04 Sv per 1 Sv and +0.07 Sv per 1 Sv, respectively. In the experiments that generate 16Sv of AMOC transport, the amplitudes of the two modes reach nearly 0.7 and 1.4Sv. Lastly, we compare the dynamical mechanisms of the two modes and their climate impacts. A corollary of this study is that in this model, a stronger AMOC would lead to stronger climate variability.
Snowball Earth initiation and the thermodynamics of sea ice
Authors: Hörner Johannes , Voigt Aiko , Braun Christoph
Published: March 2022

Snowball Earth is a hypothesized state in the deep past of Earth in which the ocean was completely or nearly completely covered by sea ice, resulting from a runaway ice-albedo feedback. Here, we address how the treatment of sea-ice thermodynamics affects the initiation of a Snowball Earth in the global climate model ICON-A run in an idealized slab-ocean aquaplanet setup. Specifically, we study the impact of vertical resolution and brine pockets of ice by comparing the 3-layer Winton and a 0-layer Semtner scheme, and we investigate the impact of limiting ice thickness to 5m.

The internal heat storage of ice is increased by higher vertical resolution and brine pockets, which weakens surface melting and increases global albedo by allowing snow and ice to persist longer into the summer season. The internal heat storage weakens the melt-ratchet effect, as is confirmed with offline simulations with the two ice schemes. The result is a substantially easier Snowball Earth initiation and an increase in the critical CO2 for Snowball initiation by 50%. Limiting ice thickness impedes Snowball initiation as the removal of excess ice leads to an artificial heat source. Yet, the impact is minor and critical is decreased by 5% only.

The results show that while the sea-ice thickness limit plays only a minor role, the internal heat storage of ice represents an important factor for Snowball initiation and needs to be taken into account when modeling Snowball Earth initiation.
Assessing Water-Energy-Food nexus synergies and trade-offs:  an ecosystems services-based perspective 
Authors: Sperotto Anna , Villa Ferdinando , Balbi Stefano , Bagli Stefano
Published: March 2022

 

Managing water, energy and food adopting a nexus approach is crucial to guarantee the sustainable and efficient use of resources, particularly in light of global changes. Ecosystem Services (ESs), namely the multiple benefits that ecosystems provide to human well-being, constitute a useful perspective to look at the critical interactions occurring between Water-Energy-Food (WEF). ESs have been rarely explicitly addressed in nexus assessment, however representing the bio-physical foundation of the WEF interactions, they can be used as common assessment endpoints permitting to better disentangle and manage cross-sectoral synergies and trade-offs. The UNTWIST project (MSCA-IF) proposes an innovative approach to look at the WEF nexus through the lens of ecosystem services theory gaining insights about potential interdependencies between sectorial policies and thus unlocking opportunities for delivering integrated solutions towards the achievement of multiple Sustainable Development Goals (SDGs). Starting from the nexus framing, a participative approach is adopted for engaging local stakeholders’ representative of different nexus sectors in identifying existing conflicts in water use and prioritizing ESs they value the most. Later, ARIES (Artificial Intelligence for Environment and Sustainability), an Artificial Intelligence modeler based on the semantic web, is used to develop an integrated model to spatially-temporally represent most relevant ESs and flows exchanged through the WEF nexus building on available sectoral data and models. The proposed approach permits to map critical areas for multiple ESs provision to WEF and thus to identify where synergies and trade-offs between sectors are likely to arise. Based on this results, different scenarios describing multiple combinations of social, economic and climatic pathways are tested serving as the basis for the definition of a shared management strategy for long-term nexus sustainability. Preliminary insights derived from the application to two different case studies in Europe (i.e. Po river basin (Italy), Pas Miera Ason river basins (Spain)) will be presented to discuss the novelty and implications of the proposed approach.

 
Drought and surface water ponding monitoring in irrigated landscapes
Authors: Sofia Giulia , Zaccone Claudio , Tarolli Paolo
Published: March 2022

Drought and surface water ponding (DSP) are one of the major natural hazards affecting crop production, especially in low-land irrigated areas.

This work focus on an irrigated area in north-eastern Italy, a territory of about 400k ha, part of the central Veneto, where water demands is met through a mechanical and well-regulated widespread distribution of water resources. For this complex landscape, reliance on weather data alone is not sufficient to monitor areas of DSP, particularly when these data can be i) untimely, sparse, and incomplete, and ii) water inflows are mechanically controlled, with varying flow exchanges, not necessarily reflecting climatic fluctuations.

Augmenting climatic data with satellite images to identify the location and severity of DSP phenomena, therefore, is a must for complete, up-to-date, and comprehensive coverage of current crop conditions.

The objective of this research is to apply and standardize open source data to augment DSP-monitoring techniques. The study was conducted with 5 years (2015-2021) of Sentinel2-10m satellite images. Z-scores of the NDVI distribution are used to estimate the probability of occurrence of the present vegetation condition at a given location relative to the possible range of vegetative vigor, historically. This information is coupled with soil data, topographic information, and accurate information on the system water fluxes, to identify and target locations more susceptible to DSP. Findings indicate that the framework, along with other monitoring tools, is useful for assessing the extent and severity of DSP at a spatial resolution of 10m. The framework is capable of providing a near-real-time indicator of vegetation conditions within irrigated regions, and, more specifically, areas of varying water management conditions.

The present study is founded by the Consorzio LEB, Cologna Veneta, Italy
The nature of the Arctic lapse-rate feedback: Spatial distribution, seasonality and trends in ERA5 and CMIP6 data
Authors: Linke Olivia , Quaas Johannes , Smith Christopher
Published: March 2022

The Arctic amplification is driven by several intertwined causes including the interplay of locally positive radiative feedbacks. The lapse-rate feedback (LRF) is a dominant driver of Arctic amplification and arises from the vertically non-uniform warming in the troposphere. In the Arctic, the LRF enforces a positive radiative feedback as the warming is most pronounced at the surface, but becomes smaller at higher altitudes which feedbacks positively on the initial greenhouse effect. This stands in contrast to the processes in the tropics, where a stronger warming of the upper troposphere dampens the greenhouse effect.

We investigate the nature of the Arctic LRF by using ERA5 Reanalyses and CMIP6 models to compute the feedback via simplified radiative transfer calculations (radiative kernels).

The Arctic LRF is unique in terms of its geographic distribution, seasonality and time evolution. From a global perspective, the LRF is most positive in Arctic winter, but shows the strongest seasonality as it becomes negative in summer over the sea ice covered ocean. Our trend analysis shows that the positive winter LRF increased strongly during the past 30 to 40 years. This increase during boreal winter mediates the annual response and accounts for all Arctic surface types which we define as sea ice, sea ice retreat, open ocean and land. A special focus lies on regions of retreating sea ice, where the positive LRF is strongest throughout the year.

Our results are embedded in previous studies on the changing Arctic atmospheric energy budget through CO2-driven climate change. They show strongly increasing surface heat fluxes over areas of retreating sea ice which is mostly compensated by a decrease in atmospheric transport convergence, both of which can shape the maximum of the high-latitude positive LRF.

We finally carry out an inter-model comparison of linear trends of the Arctic LRF during the past 30 years of historical CMIP6 simulations. This includes more than 50 models to determine the performance of each model by relating to reanalyses data.
Completing Urban GHG Emissions Data to Assess the Effectiveness of Climate Action Plans in Europe
Authors: Page Jessica , Pan Haozhi , Kalantari Zahra
Published: March 2022

Urban areas are major contributors to global greenhouse gas (GHG) emissions. To address climate change, many cities have developed climate action plans (CAPs) as strategic roadmaps to reduce their emissions and strive for emission neutrality and climate resilience by 2050 or before. It has been more than a decade since the first of these plans were put in place, and it is now important to evaluate these plans and to access whether city-level climate ambitions will be realised or perhaps need adjustment to pursue for improvements in climate resilience over time

 This work aims to further our understanding of urban GHG emissions, by completing existing urban carbon emissions data with blue-green contributions to the urban carbon cycle. In a previous study, it was found that the inclusion of blue-green emissions in urban carbon accounting in Stockholm, Sweden had a significant impact on that region’s ability to reach net zero emissions in the coming decades (Page et al., 2021). In this study, we complete the urban emissions data for cities across the European Union (EU) in order to assess if, and for which types of cities, the inclusion of blue-green emissions in the GHG accounting is similarly relevant.

Furthermore, we will use data about the CAPs produced and implemented by these cities together with the completed GHG emissions in order to assess whether the actions and plans made by many European cities have actually had any impact on the emissions from these cities. The inclusion of blue-green emissions and sequestrations in this assessment is particularly important, as many of the strategies included in CAPs impact blue-green areas, such as the implementation of nature-based solutions (NBS).

Conclusions will be drawn about the role of green-blue areas in urban GHG emissions, the role which CAPs have played in reducing emissions in European cities, and how and where these could potentially be adapted to further reduce future GHG emissions in urban areas.

Keywords: Sustainable cities; Greenhouse Gas Emissions; Nature-based Solutions; Climate Action Plans

References:

Page J, Kåresdotter E, Destouni G, et al. (2021) A more complete accounting of greenhouse gas emissions and sequestration in urban landscapes. Anthropocene 34: 100296. DOI: 10.1016/j.ancene.2021.100296.
Reversibility experiments of present-day Antarctic grounding lines
Authors: Urruty Benoit , Hill Emily A. , Reese Ronja , Garbe Julius , Gagliardini Olivier , Durand Gael , Gillet-Chaulet Fabien , Gudmundsson G. Hilmar , Winkelmann Ricarda , Chekki Mondher , Chandler David , Langebroek Petra
Published: March 2022

The stability of the grounding lines of Antarctica is a fundamental question in glaciology, because current grounding lines are in some locations at the edge of large marine basins, and have been hypothesized to potentially undergo irreversible retreat in response to climate change. This could have global consequences and raise sea levels by several metres. However, their reversibility for the current geometry has not yet been questioned, i.e. if pushed very slightly, are they able to recover their former position? 

Here we approach this question using three state-of-the-art ice sheet models (Elmer\Ice, Úa and PISM) which we initialise to closely replicate the current state of Antarctic ice sheet using inverse methods or spin-up approaches and the latest observations. To assess the reversibility of the Antarctic grounding lines in their current position, we apply a small amplitude perturbation in ice shelf melt rates for 20 years, which leads to a numerically significant grounding line retreat, but does not fundamentally alter it. After reversing the forcing we examine the grounding line evolution over the following 80 to 480 years, which allows us to see the direction of the ice sheet trajectory after removing the perturbation, i.e. recovery or further retreat. However, since ice dynamics adjust over long timescales of millennia, in some cases up to 500 years are not sufficient for the grounding lines to fully recover to their initial positions. To complement these experiments and to investigate the long-term response to small perturbations, we run the lower resolved Parallel Ice Sheet Model towards equilibrium. In this case, the perturbation is the increase from 1850 to present-day climate, and the experiments indicate whether present-day climate can cause Antarctic grounding lines to retreat on the long-term.

This work is part of the TiPACCs project and complements two presentations focusing on the short-term (EGU22-7802) and long-term (EGU22-7885) reversibility experiments of present-day Antarctic grounding lines in more detail.
How tree management affects water levels and peat properties in a groundwater fed peatland
Authors: Halliday Elaine , Clark Joanna , Verhoef Anne , Macdonald David , Wilkinson Debbie
Published: March 2022

Groundwater-fed peatlands are a rare and vital ecosystem providing rich biodiversity, carbon storage and regulation of the hydrological cycle. Management of these species and carbon stores are essential for maintaining a healthy ecosystem. In parallel to this, groundwater aquifers are a common source of relatively clean drinking water, under pressure from population growth and climate change. Groundwater abstraction can lead to a reduction in groundwater levels within associated wetlands, affecting their condition, for example by facilitating tree encroachment. Therefore, sustainable water supply needs to balance water demand against other unintentional environmental impacts on the ecosystems. Greywell Fen is located in Southern England, situated above a chalk aquifer that is used to provide drinking water to the area. The fen has been designated a site of special scientific interest (SSSI) in recognition of its important flora. However, the critical vegetation species have been declining in recent decades in favour of extensive tree growth throughout the site. New management of the area has included the reintroduction of grazing and large areas of tree clearance. Our research concerns the impacts of groundwater abstraction and woodland management on the health of the fen. Extensive water level monitoring connected to different areas of tree growth and clearance is being used to determine if tree management is having an effect on water levels within the fen. In addition, peat cores have been sampled in the different areas to determine if tree management and/or water level changes are impacting peat properties, as an indication of drying and decline in fen health. Peat properties studied include pH, water content, C:N, and organic matter decomposition. The latter was performed using FTIR spectroscopy.  The results of this in-depth monitoring are presented here.
Sharp transition to strongly anomalous transport in unsaturated porous media - Modelling and prediction
Authors: Velásquez-Parra Andrés , Aquino Tomás , Willmann Matthias , Méheust Yves , Le Borgne Tanguy , Jiménez-Martínez Joaquín
Published: March 2022

Transport processes in unsaturated porous media flows play a key role in a broad range of environmental and industrial systems. The simultaneous presence of liquid and gas in the pore space increases flow heterogeneity and fundamentally alters the observed flow patterns when compared to fully saturated systems. The introduction of the air phase leads to the development of highly structured water flow fields with preferential flow localized on a backbone and flow re-circulation occurring in flow dead-ends. However, it is unclear how saturation controls both flow statistics and transport dynamics. Here we use millifluidic experiments and high-resolution numerical simulations to develop a general theoretical framework that describes this flow re-organisation in the pore space and captures its impact on the statistics of pore-scale velocities. We observe, and predict theoretically, that this previously-identified flow structure of backbone and dead-ends induces both a drastic change in the scaling of the probability density function (PDF) of flow velocities compared to fully saturated conditions, and a sharp transition to strongly anomalous transport. From the theoretically derived velocity PDFs, we successfully predict the dynamics of advective transport for all saturation degrees using a continuous time random walk approach. These findings hence provide a new modelling framework linking flow heterogeneity to parameters that describe the liquid phase heterogeneity within the pore space.
Impacts of urbanization on summer precipitation and management of engineering infrastructure systems for Montreal
Authors: Yin Hang , Sushama Laxmi , Teufel Bernardo
Published: March 2022

Despite extensive efforts in the past few decades, it still remains a big challenge to reach a coherent and concrete conclusion on how urbanization modifies precipitation for differently located and configured cities. To investigate the impacts of urbanization on summer precipitation characteristics over Montreal, the second most populous city in Canada, two sets of high-resolution numerical simulations using the Global Environmental Multiscale (GEM) model, for consecutive summers (2015-2019), one with detailed urban representation using the Town Energy Balance (TEB) model and one without TEB, are used in this study.

To validate the performance of GEM, the simulation results are directly compared with observations from Environment and Climate Change Canada weather stations, spread across the city. Results show that GEM is able to capture the general climate characteristics such as diurnal cycles of 2-meter air temperature, relative humidity, 10-meter wind pattern, and precipitation intensity distribution reasonably well over Montreal. Comparison of the two sets of simulations shows that urbanization induces a general reduction of the total summer precipitation amount over Montreal due to decreased evapotranspiration caused by land surface modification. Results also suggest an increasing tendency of extreme precipitation amount at higher temperatures in the simulations with TEB, catalyzed by enhanced surface convergence and moisture supply. Additional sensitivity experiments helped understand how urbanization has impacted the management of various engineering systems, such as road infrastructure.  
Evaluation of the daily forecasts from the coupled Terrestrial Systems Modelling Platform (TSMP) over a regional-scale domain in Central Europe
Authors: Iakunin Maksim , Wagner Niklas , Graf Alexander , Goergen Klaus , Kollet Stefan
Published: March 2022

Prediction of numerical weather prediction and climate models are the basis for informed decision making and increased resilience to hydrometeorological extremes in many of today’s resource management challenges e.g. in the agricultural sector. Coupled multi-compartment models are capable of reproducing interactions and feedbacks in the geosystem, and have thereby demonstrated versatile tools in a variety of applications. The Terrestrial Systems Modelling Platform (TSMP, https://www.terrsysmp.org) is an integrated regional Earth system model that simulates processes from groundwater across the land surface to the top of the atmosphere on multiple spatio-temporal scales. TSMP consists of the atmospheric model COSMO (Consortium for Small-scale Modeling), the CLM (Community Land Model), and the ParFlow hydrologic model, coupled through OASIS3-MCT. This work presents an evaluation of daily deterministic 10-day forecasts of the atmospheric, surface, and groundwater states and fluxes for a heterogeneous mid mountain-ranges area in the German and Belgium Eifel-Ardennes region in Central Europe from TSMP in a monitoring setup. TSMP runs at convection-permitting resolution of 1km (atmosphere) and 0.5km (sub- and land surface) over an area of 150km x 150km, driven by ECMWF HRES forecasts through a one-way double nest. Data from the densely instrumented Eifel/Lower Rhine Valley observational network of Terrestrial Environmental Observatories (TERENO, https://www.tereno.net) is used for evaluation of the TSMP simulations. TSMP forecasts from July 2019 to July 2021 covering an agricultural and hydrological drought and the transition back to the climatological mean state are analyzed in detail. Despite the complex terrain and the free running TSMP, meteorological and hydrological station data are generally well represented while a certain overestimation of daily precipitation is observed.
Multi-GNSS Meteorology at GFZ Potsdam: Severe flood events in Germany in July 2021
Authors: Wilgan Karina , Dick Galina , Zus Florian , Wickert Jens
Published: March 2022

The year 2021 abounded in many severe weather events. The Ahr Valley flood in July, where almost 200 people have lost their lives, was the deadliest natural disaster in Germany since 1962. This shows that heavy precipitation is still one of the most dangerous weather phenomena in Europe. Improving its prediction will lead to better warning systems e.g., against flash floods, debris falls or landslides. One way of improving the forecasts is the assimilation of external data. Several weather services operationally assimilate the data from Global Navigation Satellite Systems (GNSS), mostly the GPS-only zenith total delay (ZTD) or integrated water vapor (IWV) into their Numerical Weather Models (NWMs).  

The current research project of the German Research Foundation DFG (Advanced MUlti-GNSS Array for Monitoring Severe Weather Events, AMUSE), performed in a cooperation of TUB, GFZ and the German Weather Service (DWD), focuses on the assimilation of the advanced multi-GNSS products, especially slant total delays (STDs), into NWMs. In this study, we present the derivation of the multi-GNSS (at the moment GPS/GLONASS/Galileo) tropospheric products at GFZ, i.e. the ZTDs, STDs and tropospheric gradients, for the severe floods in July 2021 in Germany. The obtained parameters are compared with the global NWMs: ERA5 reanalysis of ECMWF and two forecast models: ICON run by the DWD and GFS run by the US Weather Service. The results show that all considered GNSS solutions have a similar level of agreement with the NWMs. However, for the flood regions in the western Germany, the biases from the multi-GNSS solutions are smaller compared to the GPS-only solutions. The NWM parameters are compared also with each other. There are differences between the particular models, however, the differences are smaller than between the NWM and GNSS.