bluuebunny/crossref_metadata_2025 huggingface dataset:
Kilometer-wide volumetric deformation of the shallow crust associated with strike-slip continental earthquakes and its relation with coseismic shallow slip deficits
Authors: Antoine Solène L. , Wang Kang , Klinger Yann , Bürgmann Roland , Delorme Arthur
Published: March 2022

Surface deformation associated with continental earthquakes separates into a localized component occurring on faults, and distributed deformation affecting the surrounding medium, referred to as off-fault deformation (OFD). This OFD includes both displacement discrete on secondary faults and cracks, and more diffuse deformation affecting the bulk volume of the crust. Although the deformation occurring on faults and cracks can be observed and measured in the field, diffuse deformation is more challenging to detect because it generates kilometer-scale continuous gradients of displacement without any visible disruption of the ground surface. Consequently, surface displacements measured in the field generally underestimate the total surface displacement of the earthquakes. Moreover, results from inversions of geodetic and/or seismic data suggest that, for many earthquakes, the amount of coseismic slip occurring at depth (3-7 km) is larger than what occurs in the shallower part (<3 km). This is referred to as the shallow slip deficit (SSD). So far, because diffuse deformation is not explicitly considered in earthquake displacement budgets, and because the origin of the SSD remains debated, it is difficult to directly compare directly surface observations with modeling results. In this study, we use a set of complementary geodetic data (InSAR, GPS, high-resolution optical data) to jointly invert for the coseismic slip of the 2019 Ridgecrest earthquake sequence in Southern California (Mw6.4 and 7.1). To reproduce the rupture complexity observed in the high-resolution optical data, we use a complex fault model with increased resolution in the uppermost crust. We pay special attention that our preferred model fits both with the fault slip distribution observed at the surface in the high-resolution optical imagery data, and regional-scale displacement data from InSAR and GPS. In our best model, we estimate a 30% SSD in the upper 3 km. This value of 30% matches the amount of diffuse deformation we measured around the ruptures at the surface directly on the high-resolution optical data. From these observations, we propose that SSD is entirely balanced by the volumetric diffuse deformation, and more generally, that diffuse surface deformation is proportional to SSD. Finally, based on a compilation of published data, we show that SSD and diffuse deformation are both inversely proportional to the earthquake magnitude. Indeed, for large magnitude earthquakes, SSD and diffuse deformation are close to 0%. Conversely, for earthquakes that do not break the surface, diffuse deformation might be close to 100%. However, in this latter case, it still needs to be determined whether the diffuse deformation is only elastic, or not.
Extrapolation of solar wind parameters in three-dimensions in the inner heliosphere
Authors: Timar Aniko , Opitz Andrea , Facsko Gabor , Dalya Zsuzsanna , Koban Gergely , Biro Nikolett , Madar Akos , Nemeth Zoltan
Published: March 2022

Solar wind parameters, such as the velocity, density or pressure of the solar wind, are one of the most important factors in space physics, and their knowledge at as many points in the heliosphere as possible contributes to a broader understanding of our solar system.

Solar wind parameters at various points in the inner heliosphere are estimated using extrapolation methods. Currently, all spacecraft measuring solar wind parameters are in the ecliptic plane, thus it is enough to extrapolate the data from space probes to other spacecraft or celestial bodies near the ecliptic. Solar Orbiter, on the other hand, will soon leave the ecliptic and reach heliocentric latitudes of 34 degrees by the end of the mission, opening a new perspective.

The ballistic method extrapolates solar wind parameters in one dimension from the point of measurement to a chosen heliospheric position. The simple ballistic model considers the average rotation period of the Sun for the extrapolation in longitude while assuming a constant solar wind velocity during radial propagation. Our improved solar wind propagation model takes into account the interaction of slow and fast solar wind by applying a pressure correction during the extrapolation.

Applying this pressure-corrected ballistic method to data from solar corona models, we determined the solar wind parameters in the heliosphere in three dimensions. The advantage of our pressure-corrected ballistic method is that it is simple, it requires little calculation and it can be easily applied to the data of solar corona models in order to obtain a fast and efficient prediction in three dimensions.
Infrasound Broadband Bulletin Products of the IMS for Atmospheric Studies and Civilian Applications
Authors: Hupe Patrick , Ceranna Lars , Le Pichon Alexis , Matoza Robin S. , Mialle Pierrick
Published: March 2022

The International Monitoring System (IMS), which has been established for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) verification since the late 1990s, is supposed to detect every explosion of at least 1 kt TNT equivalent worldwide. Pressure waves in the infrasound range (between ~0.01 and 20 Hz) can efficiently propagate over long distances, depending on the winds near the stratopause. Therefore, the IMS verification technology monitoring the atmosphere comprises a global infrasound network consisting of up to 60 stations, 53 of which have already been certified. Moreover, research studies and projects have suggested infrasound observations of repeating or persistent sources for probing the winds in the middle atmosphere, where numerical weather prediction models suffer from the lack of continuous observation technologies for data assimilation. One type of repetitive source is active volcanoes. In turn, this natural hazard for civil security can be monitored using infrasound, and prototypes of applications for the release of early volcanic eruption warnings have been established. However, access to raw infrasound data or products of the IMS is limited to specific user groups, which might hinder the utilization of infrasound observations.

In this study, we present IMS infrasound open-access data products for atmospheric studies and civilian applications. For this purpose, 18 years of raw infrasound data (2003-2020) were reprocessed using the Progressive Multi-Channel Correlation method with a one-third octave frequency band configuration between 0.01 and 4 Hz. From the comprehensive detection lists of 53 stations, four products were derived that differ in frequency range and temporal resolution. These are (i) low-frequency infrasound events (0.02-0.07 Hz, 30 min), detections in the microbarom frequency range – in both (ii) a lower (0.15-0.35 Hz) and (iii) a higher (0.45-0.65 Hz) frequency spectrum (both 15 min) – and (iv) observations with relatively high centre frequencies of between 1 and 3 Hz (5 min). Along with several detection parameters, calculated quantities for assessing the relative quality of the products are provided. All four products are provided per station and include detections of volcanic eruptions, while the microbarom products best reflect the middle atmosphere dynamics. The data products are demonstrated by historical and recent examples of natural events that produced infrasound detected at IMS stations. Global compilations of the products highlight the stratospheric circulation effect in the microbarom detections.
Aerosol Mineralogical and Microphysical Study from Laboratory to Satellite Remote Sensing IASI Measurements: Application to East Asian Deserts
Authors: Alalam Perla , Herbin Hervé
Published: March 2022

Mineral dust is the most abundant natural dust in the atmosphere. It has direct and indirect effects on the radiative budget altering climate and air quality. These effects are directly dependent of the mineralogical composition and microphysical properties of the transported dust in the atmosphere.

High spectral resolution Infrared remote sensing technology has shown the ability to characterize different atmospheric components from local to global scale. In particular, the atmospheric aerosols are quantified using hyperspectral infrared spectrometers and processing algorithms since to achieve these measurements, a perfect knowledge of mineral dust optical properties is required i.e. extinction coefficient and complex refractive indices.

East Asia presents the second largest dust source in the world after Sahara. The atmospheric dust in this region has a diversity in its mineralogical composition; rich in silicates but also in carbonates that present a tracer of this region. On the other hand, the dust is uplifted in the low troposphere leaving satellite remote sensing detections with Land Surface Emissivity (LSE) constraints.

To cross these challenges, Infrared Atmosphere Sounding Interferometer (IASI) observations were used with all its advantages: continuous spectrum, day and night, ocean and land detections, high spectral resolution and low radiometric noise. A new LSE optimization method was developed to correct the IASI spectra. Then, a semi-quantitative method was applied based on laboratory measurements of suspended mineral dust coupled with optimized spectral detections, to obtain new mineralogical dust extinction weights. These weights depend on the chemical composition, the size distribution and the concentration, by this means a retrieval of the latter parameters was performed using a new radiative transfer algorithm (ARAHMIS) developed at Laboratoire d’Optique Atmosphérique (LOA).

Therefore, we present the results of dust chemical and physical parameters (mineralogy, effective radius and concentration) obtained using Infrared Atmospheric Sounding Interferometer IASI data with laboratory optical properties, during dust storm events in East Asia.
Future changes in African heatwaves and their drivers at the convective scale
Authors: Birch Cathryn , Jackson Lawrence , Finney Declan , Marsham John , Stratton Rachel , Tucker Simon , Chapman Sarah , Senior Cath , Keane Richard , Guichard Francoise , Kendon Elizabeth
Published: March 2022

The future change in dry and humid heatwaves is assessed in 10 year pan-African convective scale (4.5km) and parameterised convection (25km) climate model simulations. Compared to reanalysis, the convective scale simulation is better able to represent humid heatwaves than the parameterised simulation. Model performance for dry heatwaves is much more similar. Both model configurations simulate large increases in the intensity, duration and frequency of heatwaves by 2100 under RCP8.5. Present day conditions that occur on 3 to 6 heatwave days per year will be normal by 2100, occurring on 150-180 days per year. The future change in dry heatwaves is similar in both climate model configurations, whereas the future change in humid heatwaves is 56% higher in intensity and 20% higher in frequency in the convective scale model. Dry heatwaves are associated with low rainfall, reduced cloud, increased surface shortwave heating and increased sensible heat flux. In contrast, humid heatwaves are predominately controlled by increased humidity, which is associated with increased rainfall, cloud, longwave heating and evaporation, with dry bulb temperature gaining more significance in the most humid regions. Approximately one third (32%) of present day humid heatwaves commence on wet days, suggesting the potential for compound flood-humid heat climate extremes. Moist processes are known to be better represented in convective scale models. Climate models with parameterised convection, such as those in CMIP, may underestimate the future change in humid heatwaves, which heightens the need for mitigation and adaptation strategies and indicates there may be less time available to implement them to avoid future catastrophic heat stress conditions than previously thought.
Ground-motion simulation in the Calabrian accretionary prism (Southern Italy) using a 3D geologic-based velocity model
Authors: Sgattoni Giulia , Molinari Irene , Lipparini Lorenzo , Faenza Licia , Argnani Andrea
Published: March 2022

Ground motion prediction is one of the main goals in seismic hazard assessment. Empirical ground motion prediction equations may fail to reproduce the complexity of ground shaking in complex 3D media and therefore the use of full waveform modelling is increasingly adopted to model ground shaking. The knowledge of the 3D crustal structure in terms of geometries of the main discontinuities and velocities is fundamental to model wave propagation. However, we often lack detailed geological and geophysical information to build reliable models.

We exploit here a large set composed of high-resolution 2D and 3D seismic data and of about 40 wells with stratigraphic and velocity information, both onshore and offshore, to constrain a 3D crustal velocity model in a sector of the Calabrian accretionary prism (southern Italy). We interpret the main reflection discontinuities and constrain their depth at all available wells in the study area and we use well’s check-shots and velocity data to estimate interval-velocities of the main stratigraphic units. We then combine all depth and velocity information into a regional 3D crustal velocity model of the first 8-10 km. This is subsequently extended to a depth of ~50 km using available regional crustal models to obtain the final model used for ground motion simulation.

We implement our crustal model in the spectral-element code SPECFEM3D_Cartesian to simulate wave propagation in the 3D velocity model honoring surface topography. This allows reconstructing the low-frequency part of the waveforms (up to ~1 Hz), which is then combined with high-frequency seismograms obtained with a stochastic method following the hybrid broadband simulation approach by Graves and Pitarka (2010).

We evaluate the goodness of our model by simulating real earthquakes and comparing simulated and recorded waveforms at the available seismic stations in the area. We compare the results from our 3D model with the ones obtained using a local tomography model and the European crust model EPcrust. The maps of ground motion obtained from the simulated broadband waveforms are then compared with empirical ShakeMaps. These results will also be useful for earthquake scenario calculations, by simulating potential seismic sources identified from structural analysis of geological and seismic data.
Monitoring and assessing the developing dynamics of the gully erosion using different mapping techniques
Authors: Aleksić Milica , Danáčová Michaela , Výleta Roman , Liová Anna , Tomaščík Matúš , Hlavčová Kamila
Published: March 2022

The appearance of the water erosion can be found not only in the small mountainous catchments but also in the agricultural hillslopes. Therefore, there is a growing necessity of monitoring and analyzing the potential changes of the features representing water erosion in space and through time. When it comes to monitoring irregular shapes of grooves and gully in the landscape, various modern surveying techniques could be used. The choice of a suitable method and equipment for terrain monitoring depends on the size of the area, its use, the purpose of the research, sufficient accuracy of measurements, weather conditions, and possibly other factors. The field measurements performed in the period 2014 – 2021 will be presented in this abstract. Field measurements were performed in the Myjava hillslope on the selected erosion gully, where throughout the year 2011, seven small wooden check dams were built. The dams had a stabilization purpose. As a part of monitoring, we focused on the dynamics of changes and development of the gully using various modern monitoring and surveying techniques, such as Global Navigation Satellite Systems (GNSS), Terrestrial Laser Scanning  (TLS), and Unmanned Areal Vehicle (UAV). The process of clogging and deepening of the erosive element was evaluated in the selected profiles.

Moreover, the possibility of implementing further protective measures on minimizing the erosion process was also evaluated. Simulations with the physical erosion model SMODERP were also used in the evaluation. The results showed that the length of the erosion gully increased during the monitoring period. However, the gully is sufficiently stable. Clogging appeared in the locations where the stabilizing elements occurred in both the bottom and transverse profiles.
A decrease in rockfall probability associated with changing meteorological conditions in Germany
Authors: Nissen Katrin M. , Ulbrich Uwe , Damm Bodo
Published: March 2022

In this study we assess the influence of changes in the relevant meteorological conditions on the probability for rockfall in German low mountain regions. The study is based on data from a rockfall data base for Germany (Rupp and Damm, 2020) and a data set supplied by the Deutsche Bahn (German railway company) covering the periods 1838-2018 and 2015-2020, respectively. 

In a first approach, a logistic regression model for the probability of rockfall at a given location developed by Nissen et al. 2021 was applied to gridded meteorological station observations (RADOLAN and EOBS) ranging from the year 1950 to 2019. The logistic regression model quantifies the influence of daily precipitation, a proxy for pore water and freeze-thaw cycles on rockfall probability. A probability forecast was made for each day and location. The day-to-day variability in rockfall probability at the individual sites is high. Thus, the sign of the trends is site specific, but the majority of sites is showing a negative trend over the 70-year period investigated. The significance of the trends at most sites is below the 95% level. Sites at which the trend is statistically significant almost all show a negative trend, down to -4% per decade in terms of the annual number of days with a higher than climatological hazard. The mean probability decreased by as much as -2.3% per decade. 

The second approach is based on large-scale weather patterns. An analysis identified 3 weather pattern that occur on average at 9% of all days but include  19% of the days on which a rockfall event occurred. The trend in the number of these patterns was determined for the last 40 years. It suggests a decrease by -2.2% per decade and is not statistically significant. 
Increasing complexity of NEMO for climate applications by explicitly simulating the large sub-ice shelf seas
Authors: Hutchinson Katherine , Deshayes Julie , Éthé Christian , Rousset Clement , Vancoppenolle Martin , Jourdain Nicolas , Mathiot Pierre
Published: March 2022

None of the coupled climate models contributing to the DECK experiments of CMIP6 directly simulate ocean circulation under the ice-shelves of Antarctica, thereby omitting a potentially critical piece of the climate puzzle. Ocean-ice shelf interactions are vital to the production of Ice Shelf Water (ISW), a parent water mass of the globally important Antarctic Bottom Water (AABW). In NEMO these interactions can be explicitly represented or parameterised. For the parameterization, the cavities are left closed and the observed melt is injected along the depth interval between the ice shelf base and the bathymetry at the position of the ice shelf front. While this accounts for an input of freshwater along the Antarctic coastline, it does not allow for a change in melt rate in response to ocean conditions, nor does it adequately represent dense water production on the continental shelf. 

To address this, we explicitly simulate ocean circulation beneath three large Antarctic ice shelves thought to be responsible for the majority of dense water production feeding AABW, namely: Filchner-Ronne Ice Shelf (FRIS), Ross Ice Shelf and Larsen C Ice Shelf. All smaller cavities are provisionally left parameterized. We present a new NEMO configuration with ocean circulation under the large Antarctic ice shelves and explicit ISW formation. Results show that the grid resolution of the NEMO global 1° configuration, is sufficient to set-up sub-ice shelf circulation patterns that are in line with observations and produce melt rate patterns that agree well with both high resolution models and satellite measurements. The net melt of FRIS after 2 cycles of CORE forcing corresponding to the period 2005-2009 is 95 Gt/yr which is slightly lower than observed, while the net melt of Ross is overestimated at 125 Gt/yr (Rignot et al., 2013: FRIS = 155 Gt/yr, Ross = 48 Gt/yr). Work is in progress to address these opposing tendencies in melt rates of the two major Antarctic ice shelves, by including the effect of tides within the cavities. We propose that the next step in climate modelling be to open the ice shelf cavities where the global model grid resolution is sufficient to do so, and employ a parameterization for the small ice shelves and for the inlets of large cavities that are too small to be resolved. 
Data-driven estimation of the committor function for an idealised AMOC model
Authors: Jacques-Dumas Valérian , Dijkstra Henk , van Westen René
Published: March 2022

The Atlantic Meridional Overturning Circulation (AMOC) transports warm, saline water towards the northern North Atlantic, contributing substantially to the meridional heat transport in the climate system. Measurements of the Atlantic freshwater divergence show that it may be in a bistable state and hence subject to collapsing under anthropogenic forcing. We aim at computing the probability of such a transition. We focus on timescales of the century and on temporary collapses of the AMOC. Using simulated data from an idealized stochastic AMOC model, where forcing and white noise are applied via a surface freshwater flux, we compute the transition probabilities versus noise and forcing amplitudes.

Such transitions are very rare and simulating long-enough trajectories in order to gather sufficient statistics is too expensive. Conversely, rare-events algorithms like TAMS (Trajectory-Adaptive Multilevel Sampling) encourage the transition without changing the statistics. In TAMS, N trajectories are simulated and evaluated with a score function; the poorest-performing trajectories are discarded, and the best ones are re-simulated.

The optimal score function is the committor function, defined as the probability that a trajectory reaches a zone A of the phase space before another zone B. Its exact computation is in general difficult and time-consuming. In this presentation, we compare data-driven methods to estimate the committor. Firstly, the Analogues Markov Chain method computes it from the transition matrix of a long re-simulated trajectory. The K-Nearest Neighbours method relies on an existing pool of states where the committor function is already known to estimate it everywhere. Finally, the Dynamical Modes Decomposition method is based on a Galerkin approximation of the Koopman operator. The latter is the most efficient one for the AMOC model when using adaptive dimensionality reduction of the phase space.
Introducing ProMaIDes: A State-of-the Science Flood Risk Management Tool
Authors: Bachmann Daniel , Schotten Roman , Khosh Bin Ghomash Shahin
Published: March 2022

Floods are natural hazards with severe socio-economic and environmental impacts on affected areas and societies every year. A chain of different processes being involved in a flooding - characterized by precipitation, topography, land use etc. - complicates the understanding of the dynamics of a flood. However, the prediction of probabilities, flood hazards, flooding extents, dike failure, consequences and understanding the ongoing processes during a flood event are important issues in flood risk management. Computational modelling is a key method in supporting flood risk management and tackling the mentioned challenges.

While several computer-based models for assisting flood risk management exist, typically they concentrate on only one component of the flood risk analysis chain such as rainfall generation, hydrological/hydraulic modelling or damage analysis. They do not merge the other components on one platform which may result in encapsulated conclusions. In recent years the availability of higher detailed data, larger study domains, more computational power and more innovative models paved the way for more effective solutions.

In this work we present ProMaIDes (Protection Measures against Inundation Decision support), an open-source, free software package for risk-based evaluation of flood risk mitigation measures1. The software package consists of numerous relevant modules for a flood risk analysis in riverine and coastal regions: the HYD-module for a hydrodynamic analysis, the DAM-module for an analysis of consequences (including economical damage, consequences to people and the disruption of critical infrastructure services), the FPL-module for the reliability analysis of dikes and dunes as well as a combining RISK-module and the decision support MADM-module. To support a user-friendly model setup, visualization of input and data results, a connection with the free QGIS-system is established by QGIS-plugins and a PostgreSQL-database as data-management system. A detailed online documentation featuring theory, application and programming is available2. A community of users is currently set-up.

In order to give a better understanding and to demonstrate the capabilities of ProMaIDes, the tool itself, but also the modules combined with case studies are shortly presented.

 

1 https://promaides.h2.de

2 https://promaides.myjetbrains.com/youtrack/articles/PMID-A-7/General
Quality Control Methods in Ocean-Sea ice Coupled Data Assimilation
Authors: Paturi Shastri , Bozec Alexandra , Chassignet Eric , Garraffo Zulema , Mehra Avichal , Kleist Daryl
Published: March 2022

The purpose of employing data assimilation methods in operational ocean forecasting systems is to provide good initialization to the models and is dependent on good quality ocean observations being assimilated. Using or accepting erroneous data can result in an inaccurate analysis and alternatively, rejecting extreme or valid data can result in missing important events.

In this study two ocean-sea ice coupled systems are considered: HYCOM-CICE4 and MOM6-CICE6 at ¼-deg horizontal resolution and 41 vertical layers. The two coupled models are initialized from the World Ocean Atlas 2018 (WOA) temperature and salinity climatology for a period of 20 years. Both models are forced with GEFS (Global Ensemble Forecast System created by the National Centers for Environmental Prediction: NCEP). The data assimilation is performed on a 24-hr cycle using RTOFS-DA (Real-time Ocean Forecasting system-DA; 3DVAR) for HYCOM-CICE4 and SOCA (Sea ice Ocean Coupled Assimilation; 3DVAR) for MOM6-CICE6 to compare the data Quality Control (QC) methods. The ocean data being assimilated include satellite sea surface temperature (SST) and sea surface salinity (SSS), in-situ temperature & salinity, absolute dynamic topography (ADT), sea ice concentration.

The QC in RTOFS-DA and SOCA are fully automated and are performed through various filters applied (e.g., land-sea area fraction to eliminate satellite data near the coast, temperature inversion elimination in in-situ profile data, etc). The various QC methods in both DA systems are described. The results of the analysis and 24-forecast are compared against independent observations and statistics of the data accepted and rejected between the two DA systems are presented and discussed.
Development of a global model for zenith wet delays based on the random forest approach
Authors: Li Qinzheng , Böhm Johannes , Yuan Linguo , Weber Robert
Published: March 2022

Tropospheric delays have been a major error source for space geodetic techniques and the performance of their modeling is significantly limited due to the high spatiotemporal variability of the moisture in the lower atmosphere. In this study, tropospheric zenith wet delay (ZWD) modeling was realized based on the machine learning (random forest approach, RF) and using 10 years (2010-2019) of radiosonde measurements at 586 globally distributed stations. Subsequently, the ZWD modeling accuracy was validated based on the sounding profiles across the globe for the year 2020. We find that ZWD modeling accuracy is significantly improved by taking account meteorological parameters in the functional formulation, especially for surface water vapor pressure. When surface meteorological data are available, the RF-based ZWD models with meteorological parameterization can achieve an overall accuracy of 2.9 cm and the bias close to zero across the globe, which clearly outperforms current empirical models, such as the GPT3, or other models based on surface meteorological measurements. From the analyses of spatial characteristics of the ZWD accuracy, it can be concluded that the RF-based ZWD models especially mitigate the systematic biases in the regions with monsoon climate and tropical rainforest climate types. 
Impact of extreme events on topological robustness of infrastructure networks 
Authors: Wassmer Jonas , Marwan Norbert , Merz Bruno
Published: March 2022

Climate change is increasing the frequency of extreme weather events such as floods, making their impact on human society and ecosystems increasingly relevant. Extreme weather events can drastically influence the dynamics and stability of networked infrastructure systems like transportation networks or power grids. Local changes in the dynamics can affect the whole network and, in the worst case, cause a total collapse of the system through cascading failures. Hence, methods are needed to understand and prevent such collapses. 

In this project, we analyse the influences of flooding events on transportation networks using the Ahr valley flood of July 2021 in Germany as a case study. To this end, we set up a gravity model for road networks to compute the traffic loads. We use satellite data provided by EU Copernicus programme to access information about the state of the road network right after the flooding event. By removing flooded roads from the model, we can estimate the effect on the traffic load and identify secondarily affected roads. This approach enables us to identify and optimise critical links to ensure that affected areas are not isolated after extreme weather events and can receive disaster assistance from surrounding areas.
Open data sets on spectral properties of boreal forest components 
Authors: Rautiainen Miina , Hovi Aarne , Forsström Petri , Juola Jussi , Kuusinen Nea , Schraik Daniel
Published: March 2022

Spectral libraries of different components forming forests – such as leaves, bark and forest floor – are needed in the development of remote sensing methods and land surface models, and for understanding the shortwave radiation regime and ecophysiological processes of forest canopies. This poster summarizes spectral libraries of boreal forest vegetation and lichens collected in several projects led by Aalto University. The spectral libraries comprise reflectance and transmittance spectra of leaves (or needles) of 25 tree species, reflectance spectra of tree bark, and reflectance spectra of different types of forest floor vegetation and lichens. The spectral libraries have been published as open data and are now readily available for the community to use. 
Sources and processes of iron aerosols in a upwind megacity of Northern Pacific Ocean
Authors: Li Weijun , Zhu Yanhong , Shi Zongbo
Published: March 2022

Iron (Fe) in aerosol particles is a major external source of micronutrients for marine ecosystems, and poses a potential threat to human health. To understand these impacts of aerosol Fe, it is essential to quantify the sources of dissolved and total Fe. In this study, we applied a receptor modelling for the first time to apportion the sources of dissolved and total Fe in fine particles collected under five different weather conditions in Hangzhou megacity of Eastern China, which is upwind of East Asian outflow. Results showed that Fe solubility (dissolved to total Fe) was the largest in fog days (6.7 ± 3.0%), followed by haze (4.8 ± 1.9%), dust (2.1 ± 0.7%), clear (1.9 ± 1.0%), and rain (0.9 ± 0.5%) days. Positive Matrix Factorisation (PMF) analysis suggested that industrial and traffic emissions were the two dominant sources contributing to the dissolved and total Fe during haze and fog days through the primary emission and atmospheric processing, but natural dust minerals were the dominant source for Fe in dust days. Here the PMF identified additional 15% of dissolved Fe associated with secondary sources during haze and fog days, although it was less than 5% during dust and clear days. Transmission electron microscopy analysis of individual particles showed that approximately 76% and 87% of Fe-containing particles were internally mixed with acidic secondary aerosols in haze and fog days, respectively. Our results indicated that wet surface of aerosol particles promotes heterogeneous reactions between acidic species and anthropogenic Fe aerosol, contributing to higher Fe solubility during fog and haze days.
Logging residues promote rapid restoration of soil health after clear-cutting of rubber plantations at two sites with contrasting soils in Africa
Authors: Perron Thibaut , Kouakou Aymard , Simon Charlotte , Mareschal Louis , Gay Frédéric , Soumahoro Mouman , Kouassi Daouda , Rakotondrazafy Nancy , Rapidel Bruno , Laclau Jean-Paul , Brauman Alain
Published: March 2022

Soil health is defined as the soil's capacity to deliver ecosystem functions within environmental constraints. On tree plantations, clear-cutting and land preparation between two crop cycles cause severe physical disturbances to the soil and seriously deplete soil organic carbon and biodiversity. Rubber, one of the main tropical perennial crops worldwide, has a plantation life cycle of 25 to 40 years, with successive replanting cycles on the same plot. The aim of this study was to assess the effects of clear-cutting disturbance on three soil functions (carbon transformation, nutrient cycling and structure maintenance) and their restoration after the planting of the new rubber crop, in two contrasting soil situations (Arenosol and Ferralsol) in Côte d'Ivoire. In this 18-month diachronic study, we intensively measured soil functions under different scenarios as regards the management of logging residues and the use or not of a legume cover crop. We investigated the relationship between soil macrofauna diversity and soil heath. At both sites, clear-cutting and land preparation disturbed carbon transformation and nutrient cycling significantly and, to a lesser extent, structure maintenance function. When logging residues were applied, carbon transformation and structure maintenance functions were fully restored within 12 to 18 months after disturbance. By contrast, no restoration of nutrient cycling was observed over the study period. A legume cover crop mainly improved the restoration of carbon transformation. We found a strong relationship (P ≤ 0.001; R2 = 0.62–0.66) between soil macrofauna diversity and soil health. Our overall results were very similar at the two sites, despite their contrasting soil conditions. Keeping logging residues in the plots and sowing a legume in the inter-row at replanting accelerated the restoration of soil functions after major disturbance caused by clear-cutting and land preparation. Our results confirm the necessity of taking soil macrofauna diversity into account in the management of tropical perennial crops.
Using an open source approach to remotely collect reliable environmental data
Authors: Björner Mathis , Naumann Michael , Furkert Frederik , Stepputtis Daniel , Hermann Andreas , Gag Martin , Eilek Sebastian , Wagner Robert
Published: March 2022

Environmental monitoring programs carried out by expeditions or autonomous stations are expensive and only allow measurements for discrete times and locations. After data acquisition most of the data needs hand-operated validation and evaluation before being stored in databases.

For a higher local and temporal resolution on parameters of marine ecosystems, it is planned to extend monitoring programs by attaching a small-sized module, which combines a microcontroller with multiple sensors, to ships of opportunity or any other suitable platform. The modules design focuses on the usability, reliability and interoperability of the derived data by using metadata information and assessing in-situ which data is relevant to be measured and stored.

Using an ESP32, a popular microcontroller, to collect data from OEM sensors of different manufacturers enables a high flexibility in parameters and sensor types. The use of different OEM sensors also allows to experiment with unconventional hydrological sensors. The proposed open source module attempts to collect data as reliable as with conventional monitoring sensor systems.

This approach allows an event based data acquisition, e.g. by adjusting the sampling rate so that only as much data as necessary is measured. In order to provide precise spatio-temporal referencing, the system contains a real time clock and GPS positioning. Moreover, storing the raw data of the sensors alongside their calibration coefficients enables post-processing of the data. The ESP32 transmits the stored data to a server via WiFi or an external LTE module. From this point on, a machine-based validation, flagging of relevant data and basic visualization can assist the evaluation.

With such a module integrating multiple sensors and focusing on the interpretation and use of data starting at the measurement, reliable and pre-evaluated data from hard to access areas can be obtained and contribute to the assessment of dynamic and heterogeneous ecosystems.
Systems thinking applied to conceptual urban groundwater model development
Authors: Ntigkakis Charalampos , Thomas Brian
Published: March 2022

Urban groundwater is an often overlooked element of the wider urban water system. Complex interactions between urban groundwater and surface water may be obscured by urban infrastructure and its influence on groundwater flow. Urban groundwater models can be developed to jointly account for groundwater-surface water processes and urban infrastructure. Therefore, they can be used to simulate potential groundwater flooding, and help understand the role of groundwater in urban resilience to climate change. Attempting to capture the inherent complexity of the built environment within a model, however, may lead to increasing model uncertainty. We argue that robust urban groundwater modelling depends on a strong conceptual understanding of the groundwater system, which can lead to achieving the goal of characterising groundwater flooding.

The aim of this study is to present a conceptual groundwater model of the Ouseburn watershed in Newcastle upon Tyne, UK. The industrial heritage of the watershed, as well as the residual effects of coal mining within the urban fabric present unique challenges in conceptual groundwater model design. These challenges are further increased by the hydrogeological properties of the watershed. To this end, we developed an urban conceptual model to identify various components that synthesise the groundwater system, as well as the interactions between them.  From our conceptual model, we aim to develop a groundwater flow model that is able to capture important system interactions, thus resulting in a robust model framework to understand groundwater flooding controls.
Improving the Surface Currents from the Merging of Altimetry and Sea Surface Temperature Image in the South Indian Ocean
Authors: Chen Zhiqiang , Wang Xidong , Chen Jian
Published: March 2022

Accurate knowledge of ocean surface currents is crucial for a gamut of applications. In this study, the way in which merging altimeters composited two-dimensional sea surface height (SSH, 1/4°) with remote sensing combined sea surface temperature (SST, 9km) image improves the surface current estimates is investigated. Based on the surface quasigeostrophic (SQG) theory, we reconstruct the surface current by resolving the large scale motions, the mesoscale dynamics, and the oceanic smaller processes. Its feasibility is validated using the altimeter-derived geostrophic current (GC) and drogued drifters in the South Indian Ocean (SIO) during 2011–2015. Results of the two cases show that the effective resolution of the reconstructed surface current (RSC) has improved to 30 km after merging the high-resolution SST information, compared to 70 km of the GC. Moreover, the RSC outperforms the altimeter-derived GC in reproducing the practical dynamical processes. Over the analyzed period, compared with 841 drifters, the statistical results indicate that the RSC reduces the reconstruction errors of zonal velocity, meridional velocity, and velocity phase by about 14.6%, 45.7%, 27.0% in the SIO relative to the GC, respectively. Our method particularly improves the meridional velocity and velocity phase along the Antarctic Circumpolar Current, Agulhas Retroflection, Greater Agulhas System, and South Equatorial Current. In addition, the lower Lagrangian separation distance and higher skill score of the RSC given by Lagrangian analysis also demonstrate that the proposed method is more promising to provide essential information on ocean surface currents applications, such as water property transports, search and rescue, etc.
Snow dunes orientation in East Antarctica
Authors: Poizat Marine , Picard Ghislain , Arnaud Laurent , Amory Charles
Published: March 2022

Wind drives the formation, shape and dynamics of aeolian snow dunes. Depending on the wind regime, different bedforms are formed such as as erosional shape (sastrugi) or linear dunes, which are straight or slightly sinuous dunes. Constraining the relationship between snow dunes and wind regimes, notably orientation, is essential for a better understanding of snow redistribution and therefore local surface mass balance. Snow dunes are widely spread in the windy polar regions and have an influence on the surface energy balance. However, relative to their sand analogues there have been few investigations relating snow bedforms orientation to wind direction. In Antarctica where snow bedforms are widely spread, wind direction has been inferred from sastrugi direction, but the relationship between the orientation of dunes and wind regime remains unclear.

In this study, we present a large-scale investigation of linear dune orientation in East Antarctica related to wind direction. We used optical Sentinel-2 images to identify linear dune fields location during summer with a 10-m resolution and retrieved their orientation. Inferring wind direction and speed from ERA5 reanalysis, at 0.25° resolution, we demonstrate that linear snow dunes are found even in areas with weak mean annual wind speed, providing some insights about the conditions of their formation. In addition, the comparison between wind direction statistics (prevailing direction and constancy) and dune orientations provides new insight into the relationship between linear snow dunes and the local wind regimes.
Transient aseismic slip and crustal shortening following 2017 Iran-Iraq (Sarpol-e Zahab) Mw 7.3 Earthquake Inferred from 3 years of InSAR Observations
Authors: Guo Zelong , Motagh Mahdi , Hu Jyr-Ching , Xu Guangyu , Haghighi Mahmud Haghshenas , Bahroudi Abbas , Fathian Aram
Published: March 2022

The 2017 Mw 7.3 Sarpol-e Zahab earthquake is the largest instrumentally recorded event to have ruptured in the Zagros Fold-thrust belt. In this study, we perform multi-temporal interferometry analysis using Sentinel-1 SAR data to investigate changes in postseismic ground deformation at the Earth’s surface and interpret this change in terms of various models including kinematic afterslip, stress-driven afterslip and viscoelastic response. We show that the kinematic afterslip model can explain the postseismic deformation spatiotemporally, while the stress-driven afterslip model tends to underestimate the earlier deformation in the western part of the postseismic deformation field. The viscoelastic response, however, is negligible with the best-fitting viscosity which is on the order of 1019 Pa s. By an integrated analysis of geodetic inversion results, geological cross-section data, regional stratigraphic column and local structures, we infer that the spatial heterogeneity of frictional property of fault plane and/or more complex geological structures may explain the underfitting between the earlier postseismic deformation and the corresponding stress-driven afterslip models. Because the coseismic rupture propagated along a basement-involved fault while the postseismic slip was more likely activated the frontal structures and/or shallower detachments in the sedimentary cover, the 2017 Sarpol-e Zahab earthquake may be evidence of a typical event which contributes both of the thick- and thin-skin shortening of Zagros in both seismic and aseismic way.
Statistical Analysis of Space-times Dynamics of Extreme Precipitation
Authors: Goshtsasbpour Golbarg , Haberlandt Uwe , El Hachem Abbas , Seidel Jochen , Bárdossy András
Published: March 2022

Precipitation extremes are space-time phenomena and traditionally the statistical analyses on such occurrences have treated them merely as point events. Many of the consequences of such events like floods are related to the water volume, hence the spatial aspect of them cannot be neglected. This work aims to bring the areal aspect of the extreme rainfall into play by introducing the area into the Extreme Value Analysis (EVA) and providing Area-Depth-Duration-Frequency (ADDF) curves. For this purpose, different spatial rainfall products have been used and compared with each other. Processed raw radar data, a product of conditional merging of the radar and station data as well as the RADKLIM data (a product of the German Weather Service designed for climate research) have been used for the EVA. Unexpected patterns have been observed in the ADDF curves based on the processed radar data which were not in agreement with the assumptions of the classical approach of areal reduction factor.  Usually, it is assumed that areal precipitation extremes increase with decreasing area, so in practice reduction factors are used to estimate areal precipitation extreme values from point observations. This behavior was observed as expected mostly for durations shorter than 2 hours in all the study locations whereas the opposite was present for longer durations, where the precipitation is increasing with increasing area, so that the ADDF curves, representing different areas, show crossings at these durations. Different hypotheses about the reason for the crossings like seasonality and spatial non-stationarity have been tested and did not explain the crossings. On the other hand, the ADDF curves of the merged rainfall product hardly showed such patterns and followed the classical assumptions. Therefore, the appearance of such crossings in the ADDF curves of a spatial rain product might be an indicator of artifacts in the radar rainfall product. It has to be investigated in further tests if these results hold and if these crossings could be used as an indicator for unplausible radar data.  