bluuebunny/crossref_metadata_2025 huggingface dataset:
Salt groundwater use for industrial purposes in compliance with the equilibrium between freshwater and saltwater
Authors: Specchio Vito , Parisi Alessandro , Piccinni Alberto Ferruccio
Published: March 2022

Studies on groundwater salinity stratification interested an area under a semi-arid climate located within an industrial zone in the Taranto Province (South-Eastern Italy). Fresh groundwater circulates in a Mesozoic carbonate coastal aquifer affected by salinization due to saltwater mixing. A clay formation along the coast prevents direct contact with present seawater. 
The area is home to many companies of national and international importance that require water for their processes. The solution is to use locally available saltwater, considered a nonvaluable resource, because of the lack of surface water and use restrictions of good quality fresh groundwater. 
The study covers the area of a company that uses its domain for both quarry and landfill activities. Because fresh groundwater resources are protected, the law authorizes the company to exploit only salt groundwater to humidify the pet-coke or lope piles stored in the landfills. The moistening is intended to avoid the atmospheric dispersion of polycyclic aromatic hydrocarbons.
In the study area, with ground-level elevations around 50 m AMSL, the water table is above 2.5 m AMSL. A borehole had to reach a depth of 300 m to locate saltwater. Prospecting during drilling, including temperature and EC logs, allowed the reconstruction of the saline stratification. The elevation of saltwater top and the thickness and position of the transition zone make such stratification differ from that expected from the usual simplified laws describing the balance between fresh and salt waters in coastal aquifers. The recognized density stratification likely depends on the aquifer boundary conditions (included fresh groundwater exploitation rate), tectonic assets, and karst development. Further research may provide useful information on disturbances to fresh and salt water equilibrium that may result from direct pumping of salt water.  
Effects of land-use change in the Amazon on precipitation are likely underestimated
Authors: Baudena Mara , Tuinenburg Obbe A , Ferdinand Pendula A , Staal Arie
Published: March 2022

Land-use changes in the Amazon affect precipitation patterns, as the forest enhances precipitation levels regionally due to tree transpiration. However, it remains unclear to what extent such changes can influence precipitation. Recent studies used hydrological and atmospheric models to estimate the contribution of tree transpiration to precipitation but assumed that precipitation decreases proportionally to the transpired portion of atmospheric moisture. Here, we relaxed this assumption by, first, relating observed hourly precipitation levels to atmospheric column water vapor in a relatively flat study area encompassing a large part of the Amazon. We found that the effect of column water vapor on hourly precipitation was strongly nonlinear, showing a steep increase in precipitation above a column water vapor content of around 60 mm. Next, we used published atmospheric trajectories of moisture from tree transpiration across the whole Amazon to estimate the transpiration component in column water vapor in our study area. Finally, we estimated precipitation reductions for column water vapor levels without this transpired moisture, given the nonlinear relationship we found. Although loss of tree transpiration from the Amazon causes a 13% drop in column water vapor, we found that it could result in a 55%–70% decrease in precipitation annually. Consequences of this nonlinearity might be twofold: although the effects of deforestation may be underestimated, it also implies that forest restoration may be more effective for precipitation enhancement than previously assumed.
Overturning Variations in the South Atlantic in an Ocean Reanalyses Ensemble
Authors: Baker Jon , Renshaw Richard , Jackson Laura , Dubois Clotilde , Iovino Doroteaciro , Zuo Hao , Perez Renellys , Dong Shenfu , Kersalé Marion
Published: March 2022

The ocean's Atlantic Meridional Overturning Circulation (AMOC) has a significant influence on global climate through its meridional transport of heat and carbon. The Southern Ocean is the conduit connecting the South Atlantic Ocean to the Pacific and Indian Oceans. Thus, overturning in the South Atlantic plays a crucial role in determining the pathways of the global overturning circulation and the transports into and out of the Atlantic Ocean. Understanding the nature and causes of its multiannual to multidecadal variation in this region is critical to improve our understanding of the MOC and more accurately predict its future changes and impacts. We analyse the South Atlantic overturning at 34.5°S in an ensemble of eddy permitting ¼ degree global ocean reanalyses, constrained by observations and historical forcings, over the period 1993-2021. This overturning transport and the meridional heat transport are validated against the continuous measurements obtained along the South Atlantic Meridional Overturning Circulation – Basin-wide Array (SAMBA). The ability of each reanalysis to capture the observed changes in the overturning will be determined, providing confidence in their ability to simulate changes prior to the availability of SAMBA, and exposing their limitations. We analyse the vertical variation of the transports and their temporal variability on various timescales. This research complements previous studies investigating changes in the subtropical and subpolar North Atlantic overturning using the same reanalyses ensemble, which was shown to provide a good representation of observations.
The relation between European heat waves and North Atlantic SSTs: a two-sided composite study
Authors: Krüger Julian , Kjellsson Joakim , Pilch Kedzierski Robin , Claus Martin
Published: March 2022

The occurrence of extreme weather events has increased during the two last decades.  European heat waves are responsible for social, economic and environmental damage and are projected to increase in magnitude, frequency and duration under global warming, heightening the  interest about the contribution of different drivers. 

By using the ERA5 Re-analysis product, we performed a two-sided composite analysis to investigate a potential relation between North Atlantic sea surface temperatures (SSTs) and the near-surface air temperature (T2m) over the European continent. Here, we show that in the presence of cold North Atlantic SSTs during summer, the distribution of European T2m shifts towards positive anomalies a few days later, increasing the likelihood for heat waves. During these events a predominant wave number three pattern in addition to regionally confined Rossby wave activity  contribute to a trough-ridge pattern in the North Atlantic-European sector. Specifically, five of 17 European heat waves within the period of 1979 to 2019 could be related to a cold North Atlantic SST event a few days in advance. In the upstream analysis we identify eleven of 17 European heat waves co-existent with cold North Atlantic SSTs. 

In order to confirm the crucial role of North Atlantic SSTs for European heat waves, we analysed output from a coupled climate model, HadGEM3, with three different horizontal resolutions. The high-resolution run revealed the closest resemblance to the ERA5 data, suggesting that mechanisms on the mesoscales (<50 km) play a role in the relationship between North Atlantic SSTs and European T2m. Results also highlight the importance of using a climate model with a high horizontal resolution for the purpose of studying the variability of European heat waves.

Based upon our results, conducted with ERA5 Re-analysis and HadGEM3 data, North Atlantic SSTs provide potential predictive skill of European heat waves.
Extreme precipitation linked to convectively coupled Kelvin waves: a case study in Padang, Sumatra.
Authors: Senior Natasha , Matthews Adrian , Webber Ben
Published: March 2022

Convectively coupled equatorial Kelvin waves (CCKWs), along with other inertia-gravity waves, form an important mode of equatorial tropical rainfall variability. A CCKW with its genesis in the Indian Ocean will travel eastward with a self-similar structure, at speeds of around 12-15ms-1. Padang is an equatorial city that lies on the west coast of the island of Sumatra, Indonesia and is the first city in the path of these CCKWs. Of the 417 extreme precipitation events identified in the IMERG and TRMM datasets we find that there are 62 events that coincide with the passage of a CCKW. Further analysis reveals that there is a 55% increase in chance of observing extreme precipitation at Padang given the presence of a CCKW. Owing to its location on the coast, the diurnal cycle of precipitation at Padang is a mixture of that typical of land and sea, with peak rainfall occurring in the evening which moves offshore overnight. We find that the presence of a CCKW alters the diurnal cycle, firstly through enhancing the onshore rainfall that persists overnight and secondly through pushing the peak rainfall time to earlier in the day. We then examine a case study of a CCKW that passed over Padang on 2017-08-21 where a clear band of eastward propagating westerlies in ERA5 reanalysis 10m zonal wind coincides with a band of IMERG precipitation. These westerlies also tilt westward with height. To understand the mechanisms by which the CCKW triggers extreme precipitation, we extract key thermodynamical variables from the reanalysis, such as divergence and specific humidity, and examine 4.4km and 8.8km resolution Met UM South East Asia forecasts of the event. We discuss the performance of the forecasts in capturing the CCKW. 
On modelling of calving front positions at KNS, southwest Greenland
Authors: Christmann Julia , Loebel Erik , Rückamp Martin , Humbert Angelika
Published: March 2022

Outlet glaciers in Greenland experience a combination of seasonal and climate-driven change. In this study, we investigate the temporal evolution of the ice front position at Kangiata Nunaata Sermia (KNS), southwest Greenland. At this outlet glacier, a seasonal ice tongue forms almost every year in winter and breaks up in spring. The motion of the ice-ocean interface is one key driver of ice dynamics. Hence, it is important to understand and reconstruct terminus fluctuations. Utilizing the increasing availability of remote sensing data and deep learning algorithms, we accurately and frequently map the ice/ocean transition from optical satellite imagery. How can we incorporate that geometrical information of frontal positions into ice sheet models? The ice flow counteracts the mass loss due to iceberg calving and frontal melt. All those processes result in moving ice fronts over time. The interaction between ice flow and ice discharge is one challenge in combining observed ice front positions and modelling. We present two ways to include the geometric information of ice front positions into the Ice-sheet and Sea-level System Model (ISSM). In a first approach, we engage a level-set method to incorporate the derived calving front positions into the ice sheet model. By prescribing observed front positions, we ignore any physical basis of ice flow dynamics. However, the level-set method allows us to solve a differential equation continuous in time and space. Since we have to deal with observational gaps of ice front positions, not all stress changes caused by changing ice front positions might be resolved by this approach. In the second approach, we discuss physical drivers of terminus changes in more detail. We show parametrizations of calving and frontal melt depending on stress thresholds and subglacial water fluxes to reproduce the observed temporal evolution of the ice front position. The parametrization due to calving leads to ice loss velocities that are one order of magnitude higher than the one due to ocean melt. In the end, we want to combine both approaches to come up with an accurate parameterization of ice loss due to calving and melting, which fit observations and incorporate the physics of glacier flow.
Tipping points in hydrology: observed regional regime shift and System Dynamics modeling
Authors: Wendling Valentin , Peugeot Christophe , Grippa Manuela , Kergoat Laurent , Mougin Eric , Hiernaux Pierre , Rouché Nathalie , Panthou Geremy , Rajot Jean-Louis , Pierre Caroline , Mora Olivier , Garcia-Mayor Angeles , Ba Abdramane , Lawin Emmanuel , Bouzou-Moussa Ibrahim , Demarty Jerôme , Etchanchu Jordi , Hector Basile , Galle Sylvie , Lebel Thierry ,   TipHyc Project
Published: March 2022

River runoff and climate data existing from 1950 to present time in West Africa are analyzed over a climatic gradient from the Sahel (semi-arid) to the Gulf of Guinea (humid). The region experienced a severe drought in the 70s-90s, with strong impact on the vegetation, soils and populations. We show that the hydrological regime in the Sahel has shifted: the runoff increased significantly between pre- and post-drought periods and is still increasing. In the Guinean region, instead, no shift is observed.

This suggests that a tipping point could have been passed, triggered by climate and/or land use change. In order to explore this hypothesis, we developed a System Dynamics model representing feedbacks between soil, vegetation and flow connectivity of hillslopes, channels and aquifers. Model runs were initialized in 1950 with maps of land use/land cover, and fed with observed rainfall (climate external forcing).

The modeling results accurately represent the observed evolution of the hydrological regime on the watersheds monitored since the 50s (ranging from 1 to 50000 km²). The model revealed that alternative stable states can exist for the climatic conditions of the study period. From the model runs, we showed that the drought triggered the crossing of a tipping point (rainfall threshold), which explains the regime shift. We identified domains within the watersheds where tipping occurred at small scale, leading to larger scale shifts. This result supports that tipping points exist in semi-arid systems where ecohydrology plays a major role. This approach seems well suited to identify areas of high risk of irreversible hydrological regime shifts under different climate and land-use scenarios.
Future changes in poleward moisture transport variability associated with atmospheric rivers
Authors: Bintanja Richard , Sonnemans Jeroen , van der Wiel Karin , Kolbe Marlen , Whan Kirien , Benedict Imme
Published: March 2022

The hydrological cycle in the Arctic is intensifying due to climate change, which could modify the climate locally, but also worldwide. For example poleward moisture transport (PMT) is projected to increase in a future climate as well as its interannual variability, mainly in summer. While the first can be attributed to increased atmospheric moisture content, the cause of the latter is still uncertain. We used the global climate model EC-Earth to examine to what extent PMT variability can be linked to atmospheric rivers (ARs) in present and future climates (2C and 3C warmer than the pre-industrial climate). It is found that most PMT variability is driven by Arctic ARs, especially over the Atlantic Ocean and to a lesser extent over the Bering Strait. In years with high PMT, a relatively large share is transported by ARs, up to 50% in the present-day climate. Moreover, our findings suggest that interannual AR-related PMT variability is more sensitive to variations in AR-intensity compared to AR-frequency in the present as well as in warmer climates. This implies that increasing interannual PMT variability is dominantly driven by the increase in PMT per AR rather than the increase in AR-occurrence. Finally, our results point at a strong contribution of ARs to interannual variability of Arctic precipitation and temperature patterns.
Investigating the effects of bryophytes on carbon cycling in a temperate forest ecosystem from stable isotope composition
Authors: Gall Corinna , Maurer Alexander , Dartsch Julia , Maas Delia , Nebel Martin , Neidhardt Harald , Oelmann Yvonne , Scholten Thomas , Seitz Steffen
Published: March 2022

Nonvascular plants such as bryophytes are often overlooked; however, they are important players at the soil-atmosphere interface and affecting water exchange, nutrient fluxes or carbon storage. Bryophytes also act as soil stabilizers in a variety of ecosystems and thus contribute significantly to the mitigation of soil erosion. Nevertheless, these stabilizing effects are not completely understood, with two distinctions: Firstly, bryophytes form a physical protective barrier that prevents direct drop impact on soil. Secondly, they fix carbon and thus contribute to soil carbon storage, which in turn enhances soil aggregation. Both factors result in a reduction of soil erosion, although it is unclear to what extent. As bryophytes showed a high impact on carbon assimilation and soil carbon storage in boreal environments, gaining an understanding of these effects in a temperate forest can be a key factor in assessing the overall state of that ecosystem.

In this study, we used the stable carbon isotope ratio (δ13C) analysis as an approach to evaluate the effect of bryophytes on soil organic carbon (SOC). Furthermore, we investigated the influence of SOC on aggregate size. Soil substrates and bryophyte species were sampled in temperate forests in southern Germany with different kinds of parent material. Five sites were located in Schönbuch Nature Park next to Tübingen and one site in the Black Forest close to Freiburg. Each study site consisted of three treatments: bryophyte-covered patches, bare undisturbed soil and partial disturbed soil from forest management. In this context, it was hypothesized that there is a significant contribution of bryophytes to SOC, which is reflected by a change in isotopic signatures and aggregate sizes. Consequently, bryophyte-covered soils are assumed to exhibit higher SOC contents, form larger soil aggregates and for this reason be more resistant to soil erosion, and the contribution of bryophytes to SOC can be estimated based on the differences in the δ13C of bryophytes compared to C3 plants.

Preliminary results of two study sites revealed a distinct positive correlation between SOC and aggregate size, whereby a contribution of bryophytes to SOC could not yet be established based on δ13C values. This could be due to the different ecological structure of the two studied sites, the similarity of carbon isotope signatures of C3 plants and bryophytes, the alteration of isotope signature as a result of decomposition, and the combination of all these factors. Laboratory and data analysis of the four remaining sites is currently ongoing, so further results will be presented at EGU 2022.
Water isotopic imprints of the Pliocene Pacific Walker Circulation 
Authors: Mayer Theodor , Feng Ran , Bhattacharya Tripti
Published: March 2022

Ocean-atmosphere coupled models predict pronounced weakening of the Pacific Walker Circulation (PWC) with increasing CO2 concentration due to enhanced tropospheric stability and reduced convective mass overturning. However, current observational results are inconsistent and do not confirm a clear weakening signal. The detection of the signature of increasing CO2 is in part impeded by substantial internal variability and anthropogenic aerosol forcings. Here we explore the possibility of using a paleoclimatic analogue to understand the contemporary PWC sensitivity to CO2 changes. We focus on the interval from mid-Piacenzian (MP, 3.3 – 3.0 Ma) to early Pleistocene (~2.4 Ma). The MP had elevated CO2 concentrations (~400ppm) and geography, topology, and vegetation similar to today. Following the MP global CO2 and temperature decreased, leading to the intensification of the Northern hemisphere glaciation. We seek to identify potential proxy constraints on model simulated PWC sensitivity to CO2 forcing by focusing on changes in the hydroclimatology during this time interval. We developed several sets of isotope-tracking enabled CESM version 1.2 simulations, which utilize pre-Industrial and Pliocene boundary conditions, different CO2 levels, and water tagging of 11 oceanographic regions to track the life cycles of various water species (H216O, H218O and HD16O). Preliminary results show that Pliocene boundary conditions have little impact on the relationship between the CO2 forcing and the intensity of PWC. The precipitation δD contrast between the eastern and western tropical Pacific, scales well with the PWC strength, suggesting high potential for developing PWC strengths proxy with precipitation isotopic records from both sides of the tropical Pacific. Our ongoing work will further identify physical processes responsible for the simulated precipitation isotopic signals: i.e., whether they reflect changes in the moisture source, moisture transport, or moist convection at the destination. Additionally, prescribed-SST simulations will also be conducted to quantify the isotopic imprints of changing tropospheric instability from SST changes.
Dual-domain modeling of discharge dynamics in a laboratory-scale fractured porous matrix system
Authors: Rüdiger Florian , Dentz Marco , Nimmo John R. , Kordilla Jannes
Published: March 2022

Fracture networks often provide rapid pathways for water infiltration and play an important role for the time-dependent recharge in the vadose zone of consolidated fractured rock and karst formations. Such systems are often conceptualized using a dual-domain approach, since they can be divided into a fracture and a matrix domain. The fracture domain, especially when well connected, provides fast preferential flow paths, whereas the matrix domain usually acts as a storage due to the high contrast in hydraulic conductivities. Under partially saturated conditions, fracture-matrix interactions, i.e., imbibition of water from the fracture system into the matrix, strongly control the fracture flow progression. We conducted infiltration experiments in simple fracture-matrix systems of varying vertical length consisting of sandstone blocks, and use a dual-porosity non-equilibrium model to model the discharge dynamics and the internal fracture-matrix mass exchange. The results show strong deviations from the experimental observations when the original parameterization and model assumptions are not modified. The domain coupling, i.e., the (activated) interface area for fracture-matrix interaction, described by the matrix-fracture volume ratio (κ) was found to be the critical parameter in order to reproduce the data. While the original model assumes a perfectly coupled fracture and matrix domain, in the experiments the discrete nature of the fracture network leads to a much stronger dominance of the rapid flow domain and hence to a reduction of κ. The newly introduced (calibrated) parameter κ* includes additional effects and processes related to the time dependent evolution and smaller dynamic size of the fracture-matrix interface. Furthermore, experiments of varying total vertical system size reveal convergence toward a unique parameter set and the existence of a representative elementary volume (REV) for the chosen setup. Though it performs less well for very small systems below REV scale, the unique parameter set describes discharge dynamics in sufficiently large systems with high accuracy.
Global surface and groundwater levels - hand measurements with a mobile app.
Authors: Diederen Dirk
Published: March 2022

Water levels are a key ingredient for water resources management.

Surface water levels are monitored to manage open channels and rivers.

Groundwater levels are crucial to bridge times of drought and keep everything and everyone alive.

Worldwide, signals of changes in (ground)water levels are picked up by the GRACE satellite.

The development of groundwater use has led to depleted levels in many regions around the world [https://www.mdpi.com/2072-4292/10/6/829].

Coarse global data sets, provided by satellite gravity measurements, should be complemented with a global data set of accurate hand measurements.

Recently, we have launched our new public mobile app for (ground)water level measurements.

This means that now everyone can measure (ground)water levels, using their mobile phone.

Take a photo of a staffgauge, the surface water level will be returned!

Play a sound into a well/pvc pipe, the groundwater level will be returned!

Public measurements on this platform could hopefully lead to a consistent, global data set of high quality (ground)water level time series.

The app is currently available in the google play store as Mobile Water Manager.

Also, the app can be found at https://portal.mobilewatermanagement.com/ (chrome/safari - add to home screen for PWA).

 
Geographically varying temperature thresholds for societal attention and health impacts of heat waves
Authors: Bogdanovich Ekaterina , Guenther Lars , Reichstein Markus , Brenning Alexander , Frank Dorothea , Schäfer Mike S. , Ruhrmann Georg , Orth René
Published: March 2022

Heat waves have severe impacts on economy, ecosystems, and society. In many regions, hot temperature extremes are expected to become more frequent and intense in the future. It is not clear, however, to which extent Europeans perceive heat waves as important and potentially pressing issues, which may for example vary according to a region’s climatic conditions. We analyze and compare the response of societal attention and public health to heat waves across many European countries for the period 2010-2020. In particular, we consider Google search attention to heat waves (which summarizes relevant search requests with similar search terms and across languages), as well as related excess mortality and press mentions.

We explore several temperature-related variables in this context and find that societal attention and excess mortality are most strongly related to maximum temperatures. Further, these relationships exhibit a threshold behavior with a temperature above which the sensitivity of societal attention or excess mortality to temperature is clearly increased. Applying a piecewise regression analysis, we identify these temperature thresholds in the relationships of societal attention and mortality with temperature in each country. In general, we find higher temperature thresholds in countries with warmer climate. Thresholds vary strongly between relatively cold countries and are more similar across warmer countries. These results are consistent across Google search attention and mortality analyses, even though excess mortality tends to be less strongly related to temperature, as they are potentially affected by other factors.

The country-specific temperature thresholds identified from empirical data will further be used to study the countries’ preparedness for future climate conditions. In the next step, applying the thresholds to climate model projections, we will identify the expected annual number of relevant heat wave days and their trends until the end of the century. This allows us to identify regions and time periods with a high sensitivity to heat waves where improved management and adaptation are particularly important.
Temporal variations in spectral reflectivity and vertical cloud structure of Jupiter’s Great Red Spot and its surroundings
Authors: Anguiano-Arteaga Asier , Pérez-Hoyos Santiago , Sánchez-Lavega Agustín , Irwin Patrick
Published: March 2022

Jupiter's Great Red Spot (GRS) is a remarkable phenomenon among solar system atmospheres. In addition to its unique dynamical properties, the vertical structure of its clouds and hazes is a relevant subject of study, being of particular interest the unknown chromophore species responsible for the GRS characteristic reddish color. In a recently published paper (Anguiano-Arteaga et al., 2021) we showed the existence of a stratospheric haze (P < 100 mbar) that seemed to be compatible with the chromophore-candidate proposed by Carlson et al. (2016), although a second coloring agent located in the upper tropospheric levels (P < 500 mbar) was also suggested.

In this study, we have analyzed high-resolution images obtained with the Hubble Space Telescope’s Wide Field Camera 3 between 2015 and 2021, with a spectral coverage from the UV to the near IR, including two methane absorption bands. Following the same procedure as in our previous paper, we have obtained the spectral reflectivity of the GRS and a few dynamically interesting regions in the surrounding area under different viewing geometries.

From the measured spectra, and following the scheme proposed by Anguiano-Arteaga et al. (2021), we retrieved several key atmospheric parameters (optical depths, particle vertical and size distributions and refractive indices) for each of the regions using the NEMESIS radiative transfer suite (Irwin et al., 2008). We show the spatial and temporal variations on these parameters, including the evolution of the properties of the chromophore species.

References

- Anguiano-Arteaga, A., Pérez-Hoyos, S., Sánchez-Lavega, A., Sanz-Requena, J. F., & Irwin, P. G. J. (2021). Vertical distribution of aerosols and hazes over Jupiter's Great Red Spot and its surroundings in 2016 from HST/WFC3 imaging. J. Geophys. Res. Planets., 126, e2021JE006996 https://doi.org/10.1029/2021JE006996

- Carlson, R.W., Baines, K.H., Anderson, M.S., Filacchione, G., & Simon, A.A. (2016). Chromophores from photolyzed ammonia reacting with acetylene: Application to Jupiter’s Great Red Spot. Icarus, 274, 106-115. https://doi.org/10.1016/j.icarus.2016.03.008

- Irwin, P.G.J., Teanby, N.A., de Kok, R., Fletcher, L.N., Howett, C.J.A., Tsang, C.C.C., Wilson, C.F., Calcutt, S.B., Nixon, C.A., & Parrish, P. D. (2008). The NEMESIS planetary atmosphere radiative transfer and retrieval tool. J. of Quant. Spec. and Radiative Transfer, 109 , 1136-1150. https://doi.org/10.1016/j.jqsrt.2007.11.006
Contribution of a windthrow-affected area to the suspended sediment transport in an Alpine Mountain catchment: a focus on the snowmelt period.
Authors: Pellegrini Giacomo , Rainato Riccardo , Mao Luca , Picco Lorenzo
Published: March 2022

In many environments, climate change causes an increase in the frequency and magnitude of Large Infrequent Disturbances (LIDs). LIDs make fragile areas, as mountain basins, even more vulnerable. Among all LIDs, windthrows are one of the most relevant disturbances affecting the Alpine region. Windthrows can affect the forest cover and morphological settings at the basin scale (e.g., due to associated landslides), changing the supply of sediments to river networks and affecting the cascading processes. This work aims to measure the sediment contribution of a managed windthrow-affected area during the snowmelt (1st April - 15th June 2021) in the Rio Cordon basin (5 km2, eastern Italian Alps). The study reach crosses the area affected by windthrow and receives sediments from six sediment sources. Two multiparameter sondes measuring the turbidity and the water level were installed upstream and downstream the windthrow-affected area. Moreover, water samples and salt dilution discharge measurements were collected to obtain the rating curves and calibrate the turbidity meters in order to derive suspended sediment loads (SSL). The cumulative precipitation registered 231.2 mm during the entire 2021 snowmelt period. The total runoff recorded was 3,054,239 m3 and the total SSL at the outlet was 109 t. Two relevant events peaking at 1.13 and 1.86 m3 s-1 were recorded in the study period, and in both cases the SSL was higher at the downstream end of the reach (+4.4% and +4.0% respectively). However, clockwise hysteresis loops were identified in both sections and events. Although these preliminary results suggest that the managed windthrow-affected area can be a potential source of sediment, the greatest contribution of sediments seems to have been provided by other sediment sources, either or both located on the slopes and in the channel bed upstream the monitoring area. This study represents a suitable way of understanding the cascading processes in a mountain basin, to improve both risk-and conservation-related management strategies. Further analysis to comprehend the all-seasons basin responses are undergoing.

 
Comparison of ice dynamics using full-Stokes and Blatter-Pattyn approximation: application to the Northeast Greenland Ice Stream
Authors: Humbert Angelika , Kleiner Thomas , Rückamp Martin
Published: March 2022

Full-Stokes (FS) ice sheet models provide the most sophisticated formulation of ice sheet flow. However, their ap- plicability is often limited due to the high computational demand and numerical challenges. To balance computational demand and accuracy, the so-called Blatter-Pattyn (BP) stress regime is frequently used. Here, we explore the dynamic consequences by solving FS and the BP stress regime applied to the Northeast Greenland Ice Stream. To ensure a consistent comparison, we use one single ice sheet model to run the simulations under identical numerical conditions. A sensitivity study to the horizontal grid resolution (from 12.8 down to 0.1 km) reveals that velocity differences between the FS and BP solution emerge below ∼1 km horizontal resolution and continuously increase with resolution. Over the majority of the modelling domain both models reveal similar surface velocity patterns. At the grounding line of 79° North Glacier the simulations unveil considerable differences whereby BP overestimates ice discharge of up to 50% compared to FS. A sensitivity study to the friction type reveals that differences are stronger for a power-law friction than a linear friction law. Model differences are attributed to topographic variability and the basal drag since neglected stress terms in BP become important.
Hydrogen storage potential in the Upper Rhein Graben area
Authors: Miocic Johannes , Heinemann Niklas
Published: March 2022

Energy storage is thought to be a crucial part of renewable energy systems as it helps to alleviate the main drawbacks of renewable energy generation: their intermittency and seasonal and geographical constrains. Subsurface storage of hydrogen is one often cited option for geological energy storage and may facilitate the energy transition. Hydrogen can be stored in porous media, such as saline aquifers and depleted hydrocarbon reservoirs, and in engineered salt caverns.

The Upper Rhine Graben (URG) lies within the tri-national Upper Rhine Region where across-boarder decarbonisation scenarios require energy storage infrastructure. Here, we analyse the hydrogen storage potential of sedimentary formations within the URG based on available geological data and models. While the deeply buried sandstones of the Permo-Triassic have generally low permeabilities and porosities and only form fractured reservoirs which have limited suitability for hydrogen storage, Paleogene deposits have some storage potential and host also numerous hydrocarbon reservoirs which may be reutilised. Salt diapirs in the southern URG have the potential to hold many engineered salt caverns with significant storage potential, however the geological knowledge of the internal structure of the salt diapirs is limited. Overall, the potential of geological hydrogen storage within the URG is in the order of several TWh.

 
NO2 ship-plume segmentation with supervised learning on TROPOMI/S5P satellite data 
Authors: Kurchaba Solomiia , van Vliet Jasper , Verbeek Fons J. , Meulman Jacqueline J. , Veenman Cor J.
Published: March 2022

Starting from 2021, new and more demanding NOx emission standards came into force for ships entering the Baltic and North Sea waters. All methods that are currently used for ships compliance monitoring are expensive and require close proximity to the ship. As a result, a continuous and global execution of new regulations cannot be performed. 

The unprecedentedly high spatial resolution of the Tropospheric Monitoring Instrument onboard the Copernicus Sentinel 5 Precursor satellite (TROPOMI/S5P) allows the visual distinction of NO2 plumes produced by individual ships of substantial size. In order to have a scalable method for the estimation of NOx produced by individual ships, however, the detection of plumes needs to be automated.

Here we propose an automated approach for segmentation of NO2 plumes from individual ships using supervised learning on TROPOMI/S5P satellite data. For each ship, based on local wind conditions, as well as speed and direction (heading) of the ship, we automatically determine a Region of Interest (ROI) - an area, where the plume of the ship is expected to be located. We standardize the size and orientation of ROI, creating a standardized model of a plume - a plume cone. We then divide the plume cone into predefined subregions so that each subregion has a different probability to contain a plume of the ship. Using this information, we train a machine learning model that separates a plume produced by the analyzed ship from a background and plumes of different origin.

All studied machine learning models significantly outperform a benchmark method based on a globally optimized threshold of NO2 levels. These promising results enable us to make a next step in developing a tool for continuous NOx emission monitoring of individual ships above the open sea waters.

This work is funded by the Netherlands Human Environment and Transport Inspectorate, the Dutch Ministry of Infrastructure and Water Management, and the SCIPPER project which receives funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement Nr.814893.
Using atmospheric path-tracing as a simple hemispheric simulator to test stereo camera reconstructions of 3-dimensional boundary layer cloud fields
Authors: Burchart Yannick , Beekmans Christoph , Neggers Roel
Published: March 2022

Measurements of shallow cumulus cloud properties at meteorological sites are of crucial importance to evaluate Large-Eddy Simulations (LES) of this cloud regime, as well as its parameterized representation in numerical weather and climate models. However, to this date, these datasets have mainly consisted of vertical, one-dimensional profile data, often sampled with remote sensing equipment such as lidar or radar. A recently explored new method for adding multi-dimensional information is to use hemispheric images from a network of multiple cameras. Such networks observe shallow cumuli in unprecedented spatial detail and at ultra-high frequency. Fisheye cameras provide a large field of view, which enables the observation of complete shallow cumulus life cycles. Camera networks can thus strongly complement the existing instruments at a site, yielding unprecedented new insights into cumulus cloud field geometry, dynamics, and evolution. One possible way to independently assess the accuracy of camera networks is to apply it to virtual cloud fields as generated with LES, acting as truth in an Observation System Simulation Experiment (OSSE). However, for this purpose virtual hemispheric camera projections of the LES cloud fields are needed.

In this study, we combine Beer-Lambert radiative transfer with an open-source Monte Carlo path-tracing code to generate such projections. The method is applied to simulate a network of multiple stereo cameras as currently installed at the Jülich Observatory for Cloud Evolution (JOYCE), Germany as part of the ongoing SOCLES project. Three-dimensional LES cloud fields for selected days are used as input. Hemispheric projections are then generated and provided to the existing algorithm for generating three-dimensional fields from actual stereo camera images. Comparing the latter to the input LES fields then allows precise error estimation. One goal is to, thus, find out how much of an arbitrary three-dimensional cloud field can, in theory, be reliably detected by a stereo camera setup. A second goal is to use this information to optimize the configuration of the stereo camera network at the site.

We find that the hemispheric path tracing projections can function well in this workflow. For the selected days we find that 81% of the reconstructable cloudy grid boxes in an LES cloud field is reconstructed by the stereo camera algorithm. Modest dependence on reconstruction tolerance is reported, while dependence on camera distance is also investigated.
Evaluation of NTCM-G ionospheric delay correction model for single-frequency SPP users.
Authors: Milanowska Beata , Wielgosz Paweł , Hoque Mainul , Tomaszewski Dariusz , Jarmołowski Wojciech , Krypiak-Gregorczyk Anna , Krzykowska-Piotrowska Karolina , Rapiński Jacek
Published: March 2022

The adverse effects of ionospheric delays limit the positioning accuracy of single-frequency GNSS users. To mitigate these effects, GNSS system providers make several ionospheric delays models available for their global users. For example, the GPS has offered the Klobuchar model from the beginning. More recently, Galileo users can use the NeQuick G model. In the meantime, several independent models available for real-time navigation have emerged. Recent examples are the NTCM (Neustrelitz Total Electron Content Model) correction model provided by the German Aerospace Center (DLR) and real-time global ionosphere maps (RT-GIMs) provided by the National Centre for Space Studies (CNES).

In this contribution, we evaluate the performance of several global ionospheric delay correction models in SPP mode. We used single-frequency pseudorange data from 12 GNSS stations distributed globally, covering different latitudes for the evaluation. The test data includes GNSS observations from DOY 93/2020 to DOY 80/2021, covering almost one full year of increasing solar activity. We validated the performance of the NTCM-G model driven by the Galileo Az parameters against the Klobuchar, NeQuick 2, NeQuick G, and CNES RT GIMs models. Finally, we compared the results to reference solutions obtained with CODE GIM and also using the ionosphere-free linear combination. We showed that NTCM-G corrections presented accuracy comparable with the NeQuick G model and better than the Klobuchar one.
A Climate Change Study of Heavy Precipitation Events in the Mediterranean and Alps
Authors: Müller Sebastian K. , Pichelli Emanuela , Coppola Erika , Berthou Segolene , Brienen Susanne , Caillaud Cecile , Demory Marie-Estelle , Dobler Andreas , Feldmann Hendrik , Mercogliano Paola , Tölle Merja , de Vries Hylke
Published: March 2022

Flash floods rank among the most dangerous and costliest hazards of the alpine and mediterranean region. The severe convective storms causing them are influenced by both, the presence of a large body of sea water and a complex orography. These storms are the main subject of the present study and in the following referred to as heavy precipitation events (HPEs).

We here study heavy precipitation events by using an ensemble of convection permitting regional climate models and applying a tracking algorithm, and focus on their charateristic properties. The domain covers the Alps and the central part of the Mediterranean, and we investigate and compare three 10-year periods under the rcp85 forcing scenario: historical [2000-2009], near-future [2040-2049] and far-future [2090-2099].

Our analysis reproduces a most important message: even though in the future the mediterranean climate is drying, precipitation associated with heavy precipitation events is increasing. Further, HPEs will be more frequent in the future. In particular, their occurrence frequency will increases in wintertime, whereas it will decrease in summertime.

We investigate the climate change signal of characteristic properties describing the propagation, the spatial and temporal scales and the intensity of HPEs: on average HPEs travel by 10% farther [8km], they last longer by 5% [20 min], their area increases by 16% and their total rain volume by 34%. Regarding metrics of intensity the changes of the highest percentiles are greatest: the 90th percentiles of a HPE's precipitation field increases by 5.6%, the 99th percentile by 9.4% and the maximum increases by 12.7%.

Eventually we unravel the characterics for specific regions and seasons: changes are more dramatical for HPEs that cross the coastline and in wintertime.

In summary, this study confirms important messages of climate research in an ensemble of state-of-the-art regional climate models, demonstrates the capabilities of convection-permitting spatial resolution and explores the possibilities that come with applying a tracking algorithm and by looking into precipitation extremes in the Lagrangion framework of reference.
Detection of Solar Flares from the Analysis of Signal-To-Noise Ratio Recorded by Digisonde at Ebro Observatory
Authors: Segarra Antoni , de Paula Victor , Altadill David , Curto Juan Jose , Blanch Estefania
Published: March 2022

This work proposes a new indirect method to detect solar flares based on the effects that produce in the signal of the radio waves reflected from the ionosphere as observed by a digisonde. Analysis of the signal-to-noise ratio (SNR) measured from ionograms for Ebro Observatory ionospheric station made possible to estimate a daily pattern of the SNR under no flare conditions and to detect absorption effects in the SNR caused under flare conditions. The method allows to characterize the ionospheric absorption of High Frequency radio waves as a product of these energetic events, and provides observational data to the international Service of Rapid Magnetic Variations (SRMV) to confirm Sfe (Solar Flare Effects). To set up the method, we have analyzed a data set of solar flares occurred during 2011—2014 at daylight hours at EB040 (262 flares, 17 X-class, 124 M-class, and 121 C-class). This led to impose a minimum threshold of -20dB in the SNR for at least four consecutive frequencies to confirm that a given solar flare happened. The method is particularly sensitive in the X-class solar flares detection, performs quite well with M-class flares and even detects some C-class flares. Furthermore, we deeply studied the observational and energetic constraints that affect the detection of the solar flares from the analysis of GOES hard X-Ray; e.g. for each event, we computed the solar altitude angle at the time of the ionospheric sounding to get an estimation of the geoeffective irradiance which has an effect on the local ionosphere. According to these constraints, we can confirm that the method is more effective for detection of flares that occur when the solar elevation angle is higher than 18.94º and have a geoeffective hard X-Ray irradiance above of 3.30·10-6 W/m2.