bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical modelling of ice avalanches from the Planpincieux glacier (Italy)
Authors: Perret Paolo , Mergili Martin , Gottardelli Simone , Mondardini Luca , Segor Valerio , Troilo Fabrizio
Published: March 2022

Forward simulations of ice avalanches are important to inform risk management. However, the reliability of such simulations often suffers from the dependency of model parameters on the process magnitude, hampering the simulation of unprecedented events in a given area. We suggest a reliable, straightforward and practically applicable work flow for the forward simulation of ice avalanches for the purpose of risk management with regard to the Planpincieux glacier, located on the Italian side of Mont Blanc massif.

Since 2013, the Planpincieux glacier, has been studied to analyse the dynamics of ice collapses in a temperate glacier. Several documented ice avalanches and glacial floods (1929, 1952, 1982, 2005, 2017), which, in some cases, threatened the village of Planpincieux and damaged the municipal road, have been linked to this glacier. Starting from the summer of 2019, a fast moving ice volume, partially separated by the rest of the glacier tongue by a large crevasse, has drastically increased the occurrence of a new collapse with possible implications for the valley floor. Considering the potential risk, a glacier constant monitoring (GbInSAR) and an avalanche early warning system (avalanche Doppler radar) were deployed, and numerical modelling of ice avalanches from this glacier was made.

Thereby, we couple an empirical-statistical model with a physically-based mass flow model: (I) the rules of Alean (1985) for the angle of reach are fed into the software r.randomwalk in order to estimate worst-case reference travel distances for various scenarios of starting volumes, (II) the basal friction angle used in the physically-based tool r.avaflow is optimized against those reference travel distances for each volume scenario, (III) the travel distances and travel times are checked for plausibility against well-documented events, (IV) flow pressures and flow kinetic energies are computed with r.avaflow for each volume scenario.

The model results are well supported by empirical data for smaller events, whereas direct reference data for the larger scenarios are not available. Interpretation of the results further has to take into account that (A) for some scenarios, the empirical relationships had to be extended beyond their known range of validity, introducing additional uncertainty, and (B) the relationships do not work for snow-covered trajectories, that, for example, would decrease the friction and lead to longer travel distances. As a result, the outcomes can be, with some care, considered as worst-case assumptions for ice avalanches in summer, but are not valid for ice avalanches during the other seasons.
Precise orbit determination for the maneuvering Sentinel-3 satellites
Authors: Mao Xinyuan , Arnold Daniel , Jäggi Adrian
Published: March 2022

Low Earth orbiting (LEO) satellites require routine maneuvers to maintain the predefined trajectories. However, spaceborne scientific instruments might suffer from data discontinuities or even anomalies due to instantaneous orbit changes caused by the performed maneuvers. With the advances of spaceborne Global Navigation Satellite System (GNSS) technique, the high-low satellite-to-satellite tracking observations enable us to generate high precision satellite orbits for the nominal orbit operation periods, and more importantly, also for the maneuver periods. This research will outline the recent developments of Precise Orbit Determination (POD) for  maneuvering LEO satellites at the Astronomical Institute of the University of Bern (AIUB). The Sentinel-3 mission, an European Space Agency (ESA) Earth observation satellite formation devoted to oceanography and land-vegetation monitoring, is used as test example.

A prerequisite input for this research is the maneuver information collected by the telemetry measures which clarify the maneuver time span and accelerations. Due to unavoidable in-flight software delays and hardware performance accuracy, the maneuver information may not be perfect and needs to be improved  in the POD process. Essentially two solutions are made in this research: a. estimating the full accelerations or corrections to the known maneuver accelerations, b. estimating instantaneous velocity pulses at the requested epochs. Both algorithms are tested using the Bernese GNSS Software and POD performances for the maneuver days during 2018-2020 will be assessed. Results reveal that the post-fit carrier phase residuals can be significantly reduced, ensuring better internal consistency between the reduced-dynamic and kinematic orbit solutions. Besides, a few institution members from the Copernicus POD Quality Working Group (QWG) have been routinely generating orbit products for the maneuver days, allowing for the direct cross-validations with our new AIUB products. This research implies promising benefits to the Sentinel-3 POD and scientific research community.
Future increase in Nordic Seas overturning as a response to enhanced horizontal circulation
Authors: Årthun Marius , Asbjørnsen Helene , Chafik Léon , Johnson Helen L. , Våge Kjetil
Published: March 2022

The Atlantic meridional overturning circulation (AMOC) carries warm and saline water toward the Arctic. The North Atlantic is separated from the Arctic by the Nordic Seas. Here, the warm Atlantic inflow across the Greenland-Scotland ridge is gradually transformed by atmospheric heat loss and freshwater input as it travels along the rim of the Nordic seas and Arctic Ocean, leading to the formation of dense overflow waters that feed the lower limb of the AMOC. Recent studies have demonstrated an important role of ocean circulation and water mass transformation in the Nordic Seas for the large-scale North Atlantic circulation. Understanding future change in the Nordic Seas is therefore essential, but the impact of anthropogenic climate change on Nordic Seas circulation and overturning remains little explored.

Here we show, using large ensemble simulations and CMIP6 models, that in contrast to the overturning circulation in the North Atlantic, the Nordic Seas overturning circulation in density space shows no persistent decline in the future and is rather characterized by an increase between 2040 and 2100. This increase in Nordic Seas overturning can be explained by enhanced horizontal circulation within the interior of the Nordic Seas. The strengthened Nordic Seas overturning is furthermore found to influence overturning changes in the subpolar North Atlantic. This study thus provides evidence that the overturning circulation in the Nordic Seas could be a stabilizing factor in a weakening North Atlantic Ocean. These regionally dependent circulation changes in response to future climate change furthermore imply that current changes in the North Atlantic overturning should not be extrapolated to the Nordic Seas and Arctic Ocean.
Time evolution of the magmatic intrusion below La Palma before eruption
Authors: Fernandez Jose , Escayo Joaquin , Camacho Antonio G. , Palano Mimmo , Prieto Juan F. , Hu Zhongbo , Samsonov Sergey V. , Tiampo Kristy F. , Ancochea Eumenio
Published: March 2022

La Palma, Canary Islands, had volcanic unrest, which culminated in an eruption that started on 19 September 2021 and ended on 13 December 2021. We study the last years of this unrest using satellite radar interferometry (InSAR) and apply a novel inversion methodology to obtain information about magmatic plumbing system (MPS) configuration and its temporal evolution. The result provides the deformation sources as 3D cell aggregations for which the inversion adjustment process automatically assigns a source type (pressure change, strike-slip, dip-slip or tensile dislocation), magnitude values (MPa and cm respectively), position and orientation (angles of dislocation planes). We also update the model of the crustal structure using a novel approach. We describe the obtained results for the MPS, their relation with the crustal structure, novelties and limitations, as well as their implications at the local level, for the Canary Islands and other active areas.
Identifying hydrological planning and water management and policy issues through an iterative participatory process: A coastal tourist experience in Benidorm, Spain
Authors: Villar-Navascués Rubén , Ricart Sandra , Rico-Amorós Antonio M. , Hernández-Hernández María
Published: March 2022

Water policy and hydrological planning are critical aspects regarding water supply systems adaptation to water scarcity risk, aggravated by the uncertainties that climate change may pose on water availability. The importance of the science-policy interface is especially relevant in coupled human-nature systems where different water uses and high competition for water resources (urban, agricultural, and tourist) coexist. This situation is particularly challenging in the coastal areas of the Mediterranean, subject to summer water shortages during the consumption peaks motivated by mass-tourism activity. Although national hydrological planning already includes the primary users’ participation in revising the five-year hydrological plans to reduce water conflicts and promote collaborative water management, on numerous occasions the need to improve these processes has been evidenced to propose feasible technical and political solutions in the water sector. Taking the coastal water system of the Marina Baja, located in the province of Alicante in Southeastern Spain, as example, we carried out an iterative participatory process involving the main representatives of the water sector management and both agricultural and tourism water demands to identify which topics should be collaboratively addressed to guarantee water supply in a future climate change scenario. Stakeholders’ perceptions about the main threats and needs to improve the functioning of the water system and their influence capacity, confronted interests, and power relations have been considered. Results determined that some hydrological policies applied at a regional scale, such as protocols for the monthly water discharge of reservoirs, the setting of ecological flows, or the sanitary policies for the management of swimming pool waters, collide with the individual experience and water management protocols applied by local stakeholders. Identifying these management issues through local experiences provides evidence about particular water management and policy challenges that must be addressed to increase the adaptation capacity of water supply systems conditioned by water stress or water confronted demands to the worst forecasts of climate change.
Conceptualising the management of climate extreme events through the GIS-based digital twin system
Authors: Riaz Khurram , McAfee Marion , Anton Iulia , Gharbia Salem
Published: March 2022

Climate change has been recognised for decades, and environmental risks related to it are expected to become more common over time as the world's population continues to grow. This tendency is compounded by people congregating in areas such as coastal regions, which are becoming increasingly vulnerable due to climate change. It is demonstrated that overpopulated regions need robust early warning systems representing the region's complex systems to allow all stakeholders to receive the correct information and respond appropriately and quickly under extreme climate events to avoid losing lives and property. The concept of a 'digital twin' is proposed as an accurate virtual representation of the effect of climate events on a specific region, which can be used as a tool to achieve better resilience of cities against extreme events. A digital twin can be created by combining data from various IoT sensors and artificial intelligence with a city model to represent a digital replica of the actual world. This paper presents an up-to-date picture of the GIS-based digital twin technology developed in the last decade for the early warning of extreme climate events worldwide and their integration with the smart city management systems. The findings suggest that GIS-based digital twin technology for severe climate hazard early warning is an emerging method. Yet, it has gained prominence in recent years due to developments in technology, software development, and communication technologies. However, much more research on digital twins is necessary to create a more effective early warning system approach. This paper highlights a potential framework for the development, implementation, and application of GIS-Based digital twins in climate resilience management in coastal regions.
Stress-testing the buffering role of glaciers in the Rhine basin: How much worse could summer low flows get under future glacier retreat?
Authors: Van Tiel Marit , Weiler Markus , Freudiger Daphné , Moretti Greta , Kohn Irene , Gerlinger Kai , Stahl Kerstin
Published: March 2022

Past drought years, characterized by large scale precipitation deficits and high summer temperatures, such as 2018 in Europe, have resulted in extreme low flow situations with negative ecological, economic and social consequences. In large river basins that originate in high mountain ranges, such as the Rhine river originating in the Swiss Alps, glaciers and snowpack alleviate drought situations by continuously providing meltwater to downstream reaches during summer. However, this meltwater contribution is under threat due to ongoing climate warming and retreating glaciers. Here, we designed a stresstest model experiment to answer the question ‘what if a historical drought year reoccurs in future conditions with retreated glaciers?’ A model framework was used combining the HBV model for the glacierized headwater catchments of the Rhine and the LARSIM model for the rest of the basin. Three historical drought and low flow years, 1976, 2003 and 2018, were selected and their meteorological conditions were transferred and used as stresstest model input to three future conditions in time, namely now (2018), near future (2031) and far future (2070). These three model states were obtained by transient simulations up to the respective moment in time using meteorological observations or an ensemble of bias-corrected climate model output from the RCP 8.5 scenario, using coupled glacio-hydrological model runs. The results show an aggravation of downstream low flows, especially when drought years happen under conditions in the far future. From the three years, 2003 has the strongest effect in the future, because the ice melt contribution was highest in that year in the past. During August, flows reduce up to 80% upstream for highly glacierized catchments, compared to the streamflow of the original drought years. At downstream gauges, where flows were already critically low in the past, streamflow reduces by 5%-20%. This model experiment shows a glimpse in future low flow events and emphasizes the importance of upstream cryospheric changes for downstream streamflow dynamics during drought. 
Temporal variability of transit time distributions in response to climatic variability: do stable water isotopes and tritium tell the same tale?
Authors: Wang Siyuan , Hrachowitz Markus , Schoups Gerrit , Stumpp Christine
Published: March 2022

Transit time distributions (TTDs) of water moving through a catchment can be estimated using water isotope data. However, different isotopes are characterized by different information contents, which may affect the estimation of TTDs. Stable isotopes, such as 2H and 18O can provide insights into the part of TTDs that describes water ages of up to a few years. However, they are “blind” to ages older than that. Radioactive isotopes, such as tritium (3H), on the other hand, have been shown to describe old water, and thus the tails of TTDs much better. Direct comparisons of the different information contents and the resulting differences in catchment TTDs estimated from stable and radioactive isotopes are rare, mostly due to very limited data availability. The objectives of this study are therefore to quantify the differences in TTDs together with their temporal variability and sensitivity to climatic variability in multiple components of the hydrological system estimated from both tritium and stable isotopes using a distributed wise-process based model in the Neckar river basin in Germany. More specifically, we test the hypotheses that (1) stable isotope- and tritium-based estimates of TTDs exhibit significant differences for both young and old water ages, (2) they are characterized by distinct sensitivities to climatic variability, and that (3) combined use of stable isotopes and tritium results in more robust estimates of TTDs. The analysis is carried out based on long term hydrological (1958-2016) and isotope data (1990-2016), using a distributed hydrological model coupled with StorAge Selection (SAS) functions, which is simultaneously calibrated (and evaluated) with respect to multiple variables and hydrological signatures including, amongst others, streamflow, tritium, and stable isotope data.
Scientific and technical challenges of increasing horizontal resolution in atmospheric CO2 inversion systems
Authors: Lloret Théo , Chevallier Frédéric , Cozic Anne
Published: March 2022

The gradual densification of CO2 observation networks and CO2 observation systems around the Earth, particularly from space, has increased the observational information available for data assimilation and atmospheric inverse modeling to all spatial scales. In particular, it makes it possible to infer surface fluxes of CO2 over increasingly small regions.

This densification must be accompanied by a corresponding increase in the horizontal resolution of the transport models in which the observations are assimilated or which are inverted. In the latter application, the timescales involved extend over weeks, months or even years, and controlling computational speed despite increasing resolution is particularly critical. This challenge can be met by adapting transport models to new high-performance computing architectures and their new paradigms (multicore processors or accelerators based on graphics processing units). It deeply affects the structure of the codes, in particular the geometry of their mesh and the management of their inputs-outputs.

 

In this study, we redesign the offline transport model of the Laboratoire de Météorologie Dynamique (LMDz) Global Atmospheric General Circulation Model used in the Copernicus Atmosphere Monitoring Service inversion system (https://atmosphere.copernicus.eu/) in order to test such solutions.

First, we use a new dynamic core associated with an icosahedral-hexagonal spherical mesh, called DYNAMICO. DYNAMICO has a much better scalability than the current Cartesian grid of LMDz, while being efficiently vectorizable. Second, we use the parallel and asynchronous input-output management system called XIOS. XIOS helps damp performance losses associated with disk reads and writes.

The technical performances of the new version will be presented in the case of a regular mesh of 16,000 hexagons on the sphere, equivalent to a global resolution of about 180 km, and with 79 vertical layers, by comparison to the regular Cartesian grid. The scientific assessment is based on a large set of CO2 observations from the ground, from airplanes and from surface remote sensing reference sites. Particular attention is paid to the skill at high latitudes where the new grid avoids the singularity of the previous version at the pole, but at the cost of a coarser resolution.

 
Hybrid-Vlasov simulations of ion velocity distribution functions within Kelvin-Helmholtz vortices
Authors: Tarvus Vertti , Turc Lucile , Zhou Hongyang , Cozzani Giulia , Ganse Urs , Pfau-Kempf Yann , Alho Markku , Battarbee Markus , Bussov Maarja , Dubart Maxime , George Harriet , Grandin Maxime , Horaites Konstantinos , Manglayev Talgat , Papadakis Konstantinos , Suni Jonas , Zaitsev Ivan , Palmroth Minna
Published: March 2022

The Kelvin-Helmholtz instability (KHI) is a ubiquitous fluid instability in space plasmas. At the flanks of Earth's magnetopause, the KHI can typically develop during periods of northward interplanetary magnetic field, and it drives the solar wind-magnetosphere mass/energy transfer in the absence of dayside magnetic reconnection. We use local 2D-3V hybrid-Vlasov simulations to study the ion velocity distribution functions (VDFs) associated with the KHI in a magnetopause-like setup. Our results indicate that when the KHI enters the non-linear stage, the ion VDFs in the region perturbed by the instability become increasingly non-Maxwellian. The degree of non-Maxwellianity increases along with the magnitude of the density jump across the KHI boundary. We assess the impact of the non-Maxwellian ion VDFs on the development of the KHI, and compare the simulated VDFs with those observed by the Magnetospheric Multiscale Mission.
Combining cloud properties and synoptic observations to predict cloud base height using Machine Learning
Authors: Lenhardt Julien , Quaas Johannes , Sejdinovic Dino
Published: March 2022

Cloud base height (CBH) is an important geometric parameter of a cloud and shapes its radiative properties. The CBH is also further of practical interest in the aviation community regarding pilot visibility and aircraft icing hazards. While the cloud-top height has been successfully derived from passive imaging radiometers on satellites during recent years, the derivation of the CBH remains a more difficult challenge with these same retrievals.

In our study we combine surface observations and passive satellite remote-sensing retrievals to create a database of CBH labels and cloud properties to ultimately train a machine learning model predicting CBH. The labels come from the global marine meteorological observations dataset (UK Met Office, 2006) which consists of near-global synoptic observations made on sea. This data set provides information about CBH, cloud type, cloud cover and other meteorological surface quantities with CBH being the main interest here. The features based upon which the machine learning model is trained consist in different cloud-top and cloud optical properties (Level 2 products MOD06/MYD06 from the MODIS sensor) extracted on a 127km x 127km grid around the synoptic observation point. To study the large diversity in cloud scenes, an auto-encoder architecture is chosen. The regression task is then carried out in the modelled latent space which is output by the encoder part of the model. To account for the spatial relationships in our input data the model architecture is based on Convolutional Neural Networks. We define a study domain in the Atlantic ocean, around the equator. The combination of information from below and over the cloud could allow us to build a robust model to predict CBH and then extend predictions to regions where surface measurements are not available.
Using large samples of catchments for the regionalisation of a global hydrological model
Authors: Forstenhäusler Nicole , He Yi , Osborn Timothy J. , Bárdossy András
Published: March 2022

To obtain streamflow simulations of a sufficiently good quality, most hydrological models need to be calibrated. In case simulations are required for ungauged regions, regionalisation technique can be used to obtain the model parameters values. Here, we use a large sample of catchments across the world to calibrate and regionalise a fully-distributed version of the HBV model to simulate gridded streamflow. To regionalise the model, we linked each model parameter to a selection of catchment characteristics and used robust parameter estimation (ROPE) for calibration. Focusing on accurate simulation of high flows for flood predition, we used multiple objective functions for identifying the best-performing parameter estimates and a cross-validation procedure to validate our method and to ensure generalisability of the approach. This study forms part of a larger project aiming to improve the model’s capability to simulate future discharge in ungauged areas and thus improve our understanding of future flood risk in a changing climate.
The WINDGUST project: Results of the digitization of historical wind speed observations in Sweden
Authors: Engström Erik , Azorin-Molina Cesar , Wern Lennart , Hellström Sverker , Sturm Christophe , Joelsson Magnus , Zhou Chunlue , Chen Deliang
Published: March 2022

Global wind climate is one of the aspects of the ongoing climate change that until recent days has lacked robust knowledge of past and future trends. IPCC stated in AR6WG1 that the confidence in wind changes is “low” to “medium” which stress that there is still much to learn about wind changes and multidecadal variability in a warming climate (IPCC AR6WG1). One of the reasons have been a shortage of digitally available historical wind observations as input data to studies of historical variations in wind climate.

Here we present the results of work package 1 of the project “Assessing centennial wind speed variability from a historical weather data rescue project in Sweden” (WINDGUST, funded by FORMAS – A Swedish Research Council for Sustainable Development (ref. 2019-00509)). The WINDGUST project is a joint initiative between the Swedish Meteorological and Hydrological Institute (SMHI), the University of Gothenburg (UGOT) and the Spanish National Research Council (CSIC) aimed at filling the key gap of short availability and low quality of wind datasets, and improve the limited knowledge on the causes driving wind speed variability in a changing climate across Sweden.

In work package 1 historical wind observations from Sweden have been rescued and digitized during 2020 and 2021. Observations from 13 stations around Sweden, mostly along the coast, for the decades 1920 to 1940 were digitized, adding up to 165 stationyears of data. The digitized data from around 1920 to 2021 is freely available from the SMHI data portal: www.smhi.se/data. Meta data for the digitized stations were also collected and compiled as a support for the following quality control and homogenization in work package 2 in the WINDGUST project also presented at EGU 2022.

The work followed the “Guidelines on Best Practices for Climate Data Rescue” of the World Meteorological Organization and consisted of three steps. These three steps were: (i) designing a template for digitization; (ii) digitizing papers by an imaging process based on scanning and photographs; and (iii) typing numbers of wind speed data into the template and storing the values in the observational data base at the SMHI.

This work has partly been presented earlier in EGU2019-17792-1, EGU2020-349 and EGU21-5848.
Late Cretaceous Sevier and Laramide orogenies in Wyoming-Utah-Colorado, USA: Insight from basin subsidence history
Authors: Zhou Danya , Liu Shaofeng , Wang Lianbin , Wan Neng
Published: March 2022

The spatial and temporal variations of basin subsidence could potentially provide critical information for investigating the history of orogeny and deep mantle processes. However, due to the complexity of the formation mechanism of the Western Interior Basin, the factors controlling the basin subsidence has long been debated. Here, by reconstructing a high-resolution chronostratigraphic framework for the Upper Cretaceous strata and restoring the subsidence history of the basin, we analyze the control of the Sevier and Laramide orogenies on the Late Cretaceous evolution of the basin in the Wyoming-Utah-Colorado, and reveal the contemporary migration pattern of long-wavelength dynamic subsidence. During Cenomanian to Santonian time, thrusting events were active on the western margin of the basin, along which NS-trending long-wavelength subsidence center developed. By early Campanian (ca. 82 Ma), thrusting events developed into NW trend, and the center of long-wavelength subsidence shifted in the same orientation and gradually migrated to the center of the basin. Starting in the Maastrichtian (ca. 72 Ma), the NW-trending thrusting events migrates northeastward, roughly consistent with coeval long-wavelength subsidence center. Our results show that the former thrust event is related to Sevier orogeny, while the latter should be related to the Laramide orogeny. The initial timing of the Laramide deformation could start at as early as 82 Ma. This finding suggests that migrations of both long-wavelength subsidence center and Laramide deformation are driven by changes of Farallon subduction direction from eastward to northeastward and subduction angle from deep to flat. Our work shows how the subsidence history precisely records the timing and trajectory of Sevier and Laramide orogenies and dynamic topography, providing valuable insights for future three-dimensional modeling of dynamic subsidence in the Western Interior Basin.
Black Sea Physics Analysis and Forecasting System
Authors: Ciliberti Stefania , Jansen Eric , Azevedo Diana , Causio Salvatore , Ilicak Mehmet , Gunduz Murat , Matreata Marius , Stefanizzi Laura , Creti' Sergio , Lecci Rita , Lima Leonardo , Aydogdu Ali , Peneva Elisaveta , Coppini Giovanni , Masina Simona , Pinardi Nadia
Published: March 2022

This work presents the last version of the operational analysis and forecasting system of the physical variables and evolution plans in the Black Sea, as developed in the framework of the Copernicus Marine Service for the Black Sea Monitoring and Forecasting Centre. 

The modelling system consists of NEMO v4.0 hydrodynamical model at 1/40º resolution in horizontal and 121 vertical levels, online coupled to OceanVar for the assimilation of available insitu and satellite observations. Recently, the system has been upgraded to handle the operational historical and forecasting discharge data for the Danube River as provided by the NIHWM (Romania). Major details on the model setup and product are also available at https://resources.marine.copernicus.eu/product-detail/BLKSEA_ANALYSISFORECAST_PHY_007_001/INFORMATION. 

This contribution will focus on the description of the Black Sea Physics production unit operational capacity and on the accuracy of the delivered products by computing relevant metrics for analysis fields and forecasting skills.
Tree species diversity and functional traits in forest patches of Benin, West Africa
Authors: Agonvonon Georges A. , Azihou Akomian F. , Djagoun Chabi A. M. S. , Assogbadjo Achille E. , Ifejika Speranza Chinwe
Published: March 2022

The conservation of tree communities in forest ecosystems across the world is challenged by various anthropogenic pressures such as deforestation and fragmentation. In many areas in West Africa, fragmentation has reduced the original continuous forest ecosystems to small and isolated forest patches, mostly managed by local communities. While the importance of such small patches in biodiversity conservation is recognized in literature, evidence from tropical forest ecosystems and plant-based studies are still limited. In our study, we (i) assessed the contribution of small, unprotected forest patches to tree species conservation; (ii) determined the variation of seed dispersal syndromes in tree stands between a continuous forest and small forest patches; and (iii) identified the drivers of tree species colonization among forest patches. We sampled 69 plots in the Lama forest reserve (continuous forest) and the surrounding small isolated forest patches within 20-km radius. Trees and natural regenerations were recorded in two vegetation types including the degraded dense forest and old fallow. For each species, the IUCN conservation status and functional traits including dispersal syndrome, seed weight and maximum height were recorded. We used Generalized Linear Models to identify the determinants of immigrant regeneration densities in isolated forest patches. In total, 103 woody species were recorded and the species richness was higher in the forest patches than in the continuous forest for all vegetation types. In the dense vegetation, a similar trend was found and the number of threatened species was higher in the forest patches. Tree assemblages differed between the continuous forest and the forest patches. Tree density was higher in the continuous forest than in small forest patches. Defaunation somewhat affected the regeneration of disturbed forest patches as germination and seedling were dominated by abiotic-dispersed species and local species. Taller or heavier seed species were more likely to colonize forest patches and the density of tree species in a forest patch increased with abundance of immigrant regeneration in the nearest neighbor. We recommend the implementation of sustainable management in form of participative restoration of low-regenerated species in forest remnants  for enhanced biodiversity conservation.

Keywords: Species richness, dispersal syndrome, functional traits, fragmentation, forest patches, continuous forest
First validation of the CAMS greenhouse gas system with  IAGOS aircraft measurements of CO2 and CH4
Authors: Bennouna Yasmine , Gerbig Christoph , Clark Hannah , Agusti-Panareda Anna
Published: March 2022

IAGOS (In-service Aircraft for a Global Observing System) is a European Research Infrastructure for global observations of atmospheric composition using commercial aircraft. Commercial aircraft are ideal platforms for providing long-term in-situ measurements with high vertical and temporal resolution, particularly at cruise altitude (between 9 and 13 km) in the climate-sensitive region of the atmosphere known as the upper troposphere-lower stratosphere (UTLS) and throughout the depth of the troposphere during the landing and take off phases of the flights.  Fully automated instruments are permanently installed on Airbus A330 aircraft operated by different airlines. Data are collected on about 500 flights per aircraft per year. The aircraft measure the abundances of many essential climate variables and the data are transmitted in near real time to weather services and are freely available for the scientific community, national air quality prediction centres and the Copernicus Atmosphere Monitoring Service (CAMS).  The data are routinely used to validate the operational ECMWF chemical forecasting model through the CAMS-84 project.  Up to now this effort has focused on reactive gases and water vapour. New to IAGOS are the measurements of the greenhouse gases (GHG),  CO2 and CH4.  We present the first comparison of the CAMS GHG system  (Global analyses and high resolution forecasts of greenhouse gases) with the new IAGOS CO2 and CH4 measurements and  show how this  will  be part of  the future validation of the CAMS operational model.

 
Expanding glacier time series of Antarctica and Greenland using Soviet Era KFA-1000 satellite images
Authors: Huiban Flora , Dømgaard Mads , Girod Luc , Millan Romain , Dehecq Amaury , Mouginot Jeremie , Schomacker Anders , Rignot Eric , Bjørk Anders
Published: March 2022

Long-term records of glaciers are more than ever crucial to understand their response to climate change. High-quality photogrammetric products, Digital Elevation Models (DEMs) and orthophotographs from early satellites are essential, as they offer a unique high-resolution view on the historical glacial dynamics. However, obtaining and producing high-resolution datasets from historical imagery can be a challenge.

In our study, we are extending available satellite images time series using images from Soviet Era KFA-1000 satellite cameras. Each KFA-1000 has a 1000 mm objective, holding 1800 frames in its magazine. Each frame is typically 18x18 cm or 30 × 30 cm, with an 80 km swath width, providing panchromatic images. They supplement the very sparse data period between aerial images and high-resolution modern satellites, giving us high-resolution insight of Antarctica and Greenland dating from 1974 to 1994. Since these images have been largely underused, they have the potential to improve our knowledge of glaciers and open new scientific perspectives. They could help us improve models in studies regarding, for instance the frontal position, the flow-velocity (by doing feature tracking), the surface elevation or the grounding line of the glaciers, etc. With a spatial resolution up to 2 m and images recorded in stereo geometry, they offer a valuable complement to other historical satellite archives such as the declassified American KH imagery. Here, we use structure-from-motion (SfM) to reconstruct former glacier surfaces and flow of main outlet glaciers in both Antarctica and Greenland. We compare and assess the quality of the results by comparing the produced DEMs with recent high-resolution imagery from Worldview’s ArcticDEM. We combine the historical DEMs with recent satellite imagery of the ice elevation and reconstruct the comprehensive history of volume change over southeast and northeast Greenland glaciers since the 90s. Mostly lost from sight for 50 years, we are now resurrecting these highly valuable records and will make them freely available to science and the public.

 
Similarity and difference of Alfvén waves' propagation and evolution in the slow and fast solar wind of inner heliosphere
Authors: He Jiansen , Yang Liping , Duan Die , Zhu Xingyu , Hou Chuanpeng
Published: March 2022

Parker Solar Probe detected the Alfvénic slow solar wind in the inner heliosphere. Before that, although different spacecraft had measured that slow solar wind sometimes has Alfvénic characteristics, they did not attract extensive and strong attention and discussion. The critical question is, how does the propagation and evolution of Alfvénic waves perform through the same or different processes in the fast and slow solar wind? To study this problem, we simulate the formation of high and low-speed solar wind and the propagation of evolving Alfvén waves therein from a global perspective. Compared with one-dimensional or multi-dimensional simulations with a limited range of latitude and longitude, the advantage of global simulation is that it provides a self-consistent model of fast and slow solar wind coexisting in different flow tubes. Based on this model, we study and evaluate the effects of the expansion, bending, and non-uniformity across the flux tube on the propagation of evolving Alfvén wave. The varying characteristics during the propagation consist of wave amplitude, wave-vector anisotropy, wave mode conversion, etc. As the critical interface to distinguish the sub-Alfvénic and super-Alfvénic solar wind, which is also the vital interface to distinguish the corona and interplanetary space, Alfvén surface is another important aspect of our research. We study the propagation characteristics of Alfvén waves inside and outside the non-spherical interface. In addition, we also discuss the possible relationship between the propagation and evolution of the Alfvén wave and the formation and development of switchback.
Automatic detection of atmospheric boundary layer heights at the European scale (ABL testbed)
Authors: Kotthaus Simone , Van Hove Melania , Haeffelin Martial , Drouin Marc-Antoine , Laplace Clement , Bouffies-Cloche Sophie , Dupont Jean-Charles , Ruefenacht Rolf , Hervo Maxime , Haefele Alexander , Collaud Coen Martine , Rivier Leonard ,   PROBE ABL testbed team
Published: March 2022

A detailed understanding of atmospheric boundary layer (ABL) processes is key to improve forecasting of pollution dispersion and cloud dynamics in the context of future climate scenarios. International networks of automatic lidars and ceilometers (ALC) are gathering valuable data that allow for ABL layers to be derived in near real time. A new generation of advanced methods to automatically detect the ABL heights now exist. However, diversity in ALC models means these algorithms need to be tailored to instrument-specific capabilities.

In the framework of the ABL testbed project (funded by ICOS, ACTRIS and EUMETNET E-PROFILE), two advanced algorithms for the detection of ABL heights are being assessed for application in an operational network setting. A prime example of collaborations within the EU COST action PROBE on profiling the atmospheric boundary layer, the ABL testbed is a crucial step towards harmonised ABL height products at the European scale. A subset of 11 E-PROFILE sites in diverse geographical and land cover settings across Europe are selected where data from different ALC are available covering multiple years. Automatic layer detection is implemented, including instrument-specific corrections and calibrations. Algorithm performance for layer height detection is being evaluated via comparison of results from different ALC. Recommendations are formulated for implementation of automatic ABL height retrievals across a diverse sensor network. First results are very promising, revealing consistent temporal and spatial variations in ABL layer heights across the network.
New estimation of critical orbital forcing – CO2 relationship for triggering of glacial inception
Authors: Talento Stefanie , Willeit Matteo , Calov Reinhard , Höning Dennis , Ganopolski Andrey
Published: March 2022

Glacial inception represents a bifurcation transition between interglacial and glacial states and is governed by the non-linear dynamics of the climate-cryosphere system. It has been previously proposed that to trigger glacial inception, the orbital forcing defined as the maximum of summer insolation at 65oN and determined by Earth’s orbital parameters must be lower than a critical level. This critical level depends on the atmospheric CO2 concentration. While paleoclimatic data do not constrain the critical dependence, its accurate estimation is of fundamental importance for predicting future glaciations and the effect that anthropogenic CO2 emissions might have on them. 

In this study we use the new Earth system model of intermediate complexity CLIMBER-X (which includes modules for atmosphere, ocean, land surface, sea ice and the new version of the 3-D polythermal ice sheet model SICOPOLIS) to estimate the critical orbital forcing - CO2 relationship for triggering glacial inception. We perform a series of experiments in which different combinations of orbital forcing and atmospheric CO2 concentration are maintained constant in time. Each model simulation is run for 1 million years using an acceleration technique with asynchronous coupling between the climate and ice sheet model components. SICOPOLIS is applied only to the Northern Hemisphere with a 40 km horizontal resolution.

We analyse for which combinations of orbital forcing and CO2 glacial inception occurs and trace the critical relationship between them, separating conditions under which glacial inception is possible from those where glacial inception is not materialised. We study how adequate it is to use the maximum summer insolation at 65°N as a single metric for orbital forcing, as well as consider the differential effect each one of Earth’s orbital parameters might have. In addition, we investigate the spatial and temporal patterns of ice cover during glacial inception under different orbital forcings.
Methane emissions from abandoned wells? A German case study
Authors: Jordan Sebastian F. A. , Schlömer Stefan , Krüger Martin , Blumenberg Martin
Published: March 2022

Methane recently became the focus of attention as the target to slow global warming in the near future. Hence, measures to reduce anthropogenic methane emission are globally discussed and researchers test methods to actively reduce atmospheric methane levels. Complicating advancement in this field, there are still high uncertainties associated with methane sources and sinks. One example is the methane emission from abandoned oil and gas wells. The USA, with about 4,000,000 abandoned wells, is the only country worldwide to include emissions from these wells in their yearly greenhouse gas emissions inventory. Studies estimated that these emissions account for about 1–13% of the U.S. energy sector (Williams et al. 2021). In addition to the USA, only a few countries like Canada, the United Kingdom and the Netherlands collected data on methane emissions from abandoned gas wells. Currently Germany has about 20,000 abandoned wells (formerly productive and dry wells) of different ages, which were generally filled and buried and since 1950s officially have to be plugged, cut, and buried at the end of their lifecycle. It is unclear, whether they are emitting methane or not.

Here, we present our project to fill this knowledge gap for Germany and focus on onshore-abandoned oil & gas wells and their potential to emit methane. Therefore, we will measure soil-atmosphere methane fluxes at several abandoned wells exemplary in four regions of Lower Saxony (Federal State in Northern Germany). In case of methane emission to the atmosphere, we will determine the origin of the methane in soil gas at 1 m depth by isotopic analyses. In addition to these analyses in the direct vicinity of the boreholes, we will investigate the surrounding natural methane situation in groundwater and soil with the help of molecular-geomicrobiological methods and determinations of methane oxidation rates.

 

 

Williams, J. P., Regehr, A., & Kang, M. (2021). Methane Emissions from Abandoned Oil and Gas Wells in Canada and the United States. Environ Sci Technol, 55(1), 563-570. https://doi.org/10.1021/acs.est.0c04265
The life cycle of a foreland basin: Insights from the Alborz Mountains (Arabia-Eurasia collision zone)
Authors: Ballato Paolo , Stockli Daniel F. , Hassanzadeh Jamshid , Stockli Lisa D. , Strecker Manfred R.
Published: March 2022

Flexural foreland basins represent first-order geological archives that preserve the record of orogenic processes. These detrital archives provide critical insights into tectonic, climatic and environmental evolution as well as variations in source lithologies, isostasy, eustasy and dynamic lithospheric processes. In this study, we combine published geological data (e.g., facies analysis, magnetostratigraphy, sediment provenance, and carbon and oxygen isotopic records from authigenic minerals) with new zircon U-Pb geochronologic and zircon and apatite (U-Th)/He thermochronologic data from the southern foreland basin of the Alborz Mountains in northern Iran. This orogen, resulting from the Neogene Arabia-Eurasia collision zone, experienced topographic growth and exhumation since ~20 Ma and foreland deposition of a thick pile (> 7 km) of continental red beds.

The foreland-basin fill consists of three major systematic coarsening-upward cycles that each exhibits fine-grained siliciclastic strata at the base with high sediment accumulation rates and younger detrital zircon U-Pb and (U-Th)/He ages (mostly Eocene), followed by coarse-grained sedimentary strata with decreased sediment accumulation rates and older detrital zircon U-Pb and (U-Th)/He ages (> 100 Ma).

The base of each cycle is interpreted as a pulse of enhanced subsidence driven by tectonic loading associated with the growth of new thrust sheets experiencing erosional unroofing. The top of each cycle is interpreted to reflect wanning tectonic subsidence in response to local intra-basinal uplift (cycle 1) as documented by the sedimentary stratal pattern; uplift of the proximal foreland (cycle 3) as suggested by the age distribution of the detrital zircon U-Pb ages, the shift from fluvial to alluvial fan deposits and recycled apatite (U-Th)/He ages from the deepest exhumed red beds. Within these systematic trends, the top of cycle 2 represents an exception as it appears to record an enhanced phase of sediment supply triggered by wetter climatic conditions as documented by oxygen isotope data from paleosols samples.

Overall, our multidisciplinary approach provides a comprehensive overview of the history of a collisional foreland basin, from the forcing mechanisms controlling its stratigraphic architecture and sedimentary composition to its final incorporation into the orogenic wedge associated with basin uplift and erosion.