bluuebunny/crossref_metadata_2025 huggingface dataset:
TROPOMI observations of total column water vapor
Authors: Chan Ka Lok , Slijkhuis Sander , Garane Katerina , Valks Pieter , Loyola Diego
Published: March 2021

We present the total column water vapor (TCWV) retrieval for the TROPOspheric Monitoring Instrument (TROPOMI) observations in the blue band. The retrieval was first developed to retrieve TCWV from Global Ozone Monitoring Experience 2 (GOME-2). We have modified the settings of the retrieval to adapt it for TROPOMI observations. The TROPOMI TCWV retrieval algorithm consists of two major steps. The first step is the retrieval of water vapor slant columns by applying the differential optical absorption spectroscopy (DOAS) technique to TROPOMI observations in the blue band. The retrieved water vapor slant columns are then converted to vertical columns using air mass factors (AMFs). An iterative optimization has been developed to dynamically find the optimal a priori water vapor profile for AMF calculation. The dynamic search algorithm makes use of the fact that the vertical distribution of water vapor is strongly correlated to the total column amount. This makes the algorithm better suited for climate studies compared to typical satellite retrievals with static a priori or vertical profile information from the chemistry transport model (CTM). Details of the TCWV retrieval are presented. The TCWV retrieval algorithm is applied to TROPOMI observations. The results are validated by comparing to Ozone Monitoring Instrument (OMI), GOME-2 and Special Sensor Microwave Imager Sounder (SSMIS) satellite observations. TCWV derived from TROPOMI observations agree well with the other data sets with Pearson correlation coefficient (R) ranging from 0.94 to 0.99. The correlation is slight better during winter time of the northern hemisphere. Small discrepancies are found among TROPOMI, OMI, GOME-2 and SSMIS observations. The discrepancies are mainly due to differences in measurement time and cloud filtering. More detailed validation against ground based sun-photometer observations are presented separately in this session*.

 

*see the respective abstract by Katerina Garane.
It is not plants alone – Protozoic silica and its role in terrestrial silicon cycling
Authors: Puppe Daniel
Published: March 2021

Biogenic silicon (BSi) has been found to play a fundamental role in the link between global Si and carbon cycles, because it represents a key factor in the control of Si fluxes from terrestrial to aquatic ecosystems. Furthermore, various beneficial effects of Si accumulation in plants have been revealed, i.e., increased resistance against abiotic and biotic stresses. Thus Si is of great importance for agricultural plant-soil systems. Due to intensified land use humans directly influence Si cycling on a global scale. For example, Si exports through harvested crops and increased erosion rates generally lead to a Si loss in agricultural systems with implications for Si bioavailability in agricultural soils, which is controlled by BSi to a great extent. However, while corresponding research on phytogenic BSi (i.e., BSi synthesized by plants) has been established for decades now, studies dealing with protozoic BSi (i.e., BSi synthesized by testate amoebae) have been conducted just recently. By reviewing these studies I found them to indicate that testate amoebae might play a key role in Si cycling in terrestrial ecosystems. Actually, annual biosilicification rates of idiosomic testate amoebae are comparable to or even exceed annual Si uptake rates of trees. Furthermore, it is most likely that total protozoic Si pools (considering not only intact shells but also single idiosomes, the building blocks of testate amoeba shells) are much bigger than given in publications yet, because it can be assumed that idiosomes most likely can be as stable as phytoliths (representing the phytogenic Si pool in soils), and thus are well preserved in soils. Consequently, it would be not surprising if total protozoic Si pool quantities (shells plus single idiosomes) would be found to equal phytogenic Si pool quantities in soils. With my contribution I would like to encourage further field and laboratory research to verify this assumption and gain a deeper understanding of Si cycling by testate amoebae in terrestrial ecosystems.
Love wave or slip wave?
Authors: Kunnath Ranjith
Published: March 2021

A model that explains the anomalies in the Love wave dispersion in the earth is presented. Conventionally, welded contact between the crust and the upper mantle is assumed, leading to Love wave generation when the earth is excited. However, the observations of SH wave dispersion at seismic frequencies is at variance with this model, at least for some crustal plates (Ekström, 2011). When frictional slip occurs at the crust-upper mantle interface, a new type of interfacial elastic wave called the antiplane slip wave can occur (Ranjith, 2017). It is shown that the antiplane slip waves can explain the observed anomalies in the Love wave dispersion. 
RETREAT: A new freely available data set of  Sentinel-1 glacier velocities in regions outside the polar ice sheets
Authors: Friedl Peter , Seehaus Thorsten , Braun Matthias
Published: March 2021

Climate induced glacier change has important implications for global sea level rise, freshwater availability and geomorphologic hazards. Changes in ice dynamics and mass flow can globally be observed by long- and short-term changes in ice surface velocity. Consistent and continuous data on glacier surface velocity are important inputs to time series analyses, numerical ice dynamic modelling and glacier mass balance calculations. Therefore, glacier surface velocities have been identified as an Essential Climate Variable (ECV) that should be monitored on a regular and global scale. Since 2014, repeat-pass Synthetic Aperture Radar (SAR) data, acquired by the Sentinel-1 constellation as part of ESA’s (European Space Agency) Copernicus program, enable global, near real time-like and fully automatic processing of glacier velocity fields at up to 6-day temporal resolution, independent of weather conditions, season and daylight.

We present a new near-global data set of Sentinel-1 glacier velocities that comprises continuously updated image pair velocity fields, as well as monthly and annually averaged velocity mosaics at 200 m spatial resolution, derived from applying intensity feature tracking on both archived and new acquisitions. The data set covers all major glaciated regions outside the polar ice sheets and is generated in an HPC (High Performance Computing) environment at the University of Erlangen-Nuremberg. By the beginning of January 2021, we processed more than 110.000 Sentinel-1 scenes, amounting to roughly 450 TB of data. The velocity products are freely accessible via an interactive web portal (http://retreat.geographie.uni-erlangen.de) that provides capabilities for download and simple online analyses. We give information on the procedures of data generation, as well as on how to access the data and demonstrate the capabilities of our products for velocity time series analyses at very high temporal resolution. We compare our data to velocity products generated from very high resolution TerraSAR-X SAR (Synthetic Aperture Radar) and Landsat-8 optical (ITS_LIVE, GoLIVE) data. For this comparison we selected Svalbard as an example region, as it includes glaciers of a broad variety of sizes, different velocitiy magnitudes and seasonal velocity patterns, as well as very fast flowing surging glaciers and almost featureless ice caps.
Removal performance of faecal indicators by natural and silver-modified zeolites under dynamic batch experiments
Authors: Syngouna Vasiliki I. , Skandalis Ioannis , Vantarakis Apostolos
Published: March 2021

The use of natural zeolites (NZs) in waste-water treatment plants is one of the oldest and most promising applications.  Modified natural zeolites (MZs) have shown improved ion exchange and adsorption capacities and have been extensively applied for the removal of pollutants (metal(loid) ions, ammonia etc) from aqueous solutions. However, MZs application in biological pollutants such as indicator organisms or pathogens has not been extensively explored. This study examines the antimicrobial effect of both natural Greek zeolite (NZ), with clinoptilolite content up to 85% (OLYMPOS SA), and modified Greek zeolite by incorporation with silver ions (Ag-MNZ) on the survival of two selected bacteria. The chosen organisms, Escherichia coli and Enterococcus faecalis, constitute indicators of fecal contamination in both soils and water. Scanning electron microscopy and energy dispersive X-ray detection (SEM-EDX) were used for the surface morphology and elemental composition of the NZ and Ag-MNZ samples, respectively. A series of dynamic batch experiments were conducted at constant room temperature (22°C) in order to examine the inactivation of the above bacteria by NZ and Ag-MNZ.  It was found that the Ag-MNZ resulted in much higher reduction of the bacterial numbers when compared to the NZ and control (absence of zeolites). Moreover, the reduction in the bacterial numbers was affected by NZ particle size with higher reduction observed for coarse (1-3 mm) than fine (0-1) NZ. Finally, the E. faecalis was found to be more resistant than E.coli to Ag-MNZ.
Variations of energetic particle fluxes after interplanetary shock arrivals and around significant geomagnetic storms observed by low altitude spacecraft
Authors: Gohl Stefan , Němec František , Parrot Michel
Published: March 2021

We analyze variations of energetic particle fluxes measured by low altitude spacecraft after interplanetary shock arrivals and around the times of significant geomagnetic storms. Data from two different spacecraft and energetic particle detectors are used and compared. First, we use data measured by the energetic particle detector (IDP) onboard the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) spacecraft. The spacecraft operated between 2004 and 2010 on a circular Sun-synchronous orbit at an altitude of initially 710 km, which was decreased to 660 km in December 2005. The IDP instrument measured electron flux close to the loss cone at energies between about 70 keV and 2.3 MeV (128 energy channels). Second, we use data measured by the Space Application of Timepix Radiation Monitor (SATRAM) onboard the Proba-V satellite operating since May 2013 on a circular Sun-synchronous orbit at an altitude of 820 km. The semi-conductor based pixelated radiation detector called Timepix is capable of detecting all charged particles and X-rays with sufficiently high energies. Electron energies higher than about 2 MeV and proton energies higher than about 20 MeV are detected. We identify the times of interplanetary shock arrivals and significant (Dst < –100 nT) geomagnetic storms during the mission durations. Then we perform a superposed epoch analysis to reveal characteristic particle flux variations around these times at different energies and L-shells. Although the used satellite missions do not overlap in time, we aim to compare the revealed flux variation signatures between these two independent data sets.
Exploring the influence of plant trait diversity on climate using the plant trait diversity model JeDi-BACH in an Earth system model
Authors: Hu Pin-hsin , Reick Christian H. , Kleidon Axel , Claussen Martin
Published: March 2021

To understand the interaction between vegetation and the climate, Dynamic Global Vegetation Models (DGVMs) have been coupled with Earth system models (ESMs). In DGVMs, global vegetation is commonly empirically categorized into a few discrete plant functional types (PFTs) by differentiating their phenological, morphophysiological, and bioclimatic properties. Although the PFT-approach is useful to capture the large-scale general features of plants, growing evidence from the ecology community has challenged the use of the plant-type specific parametrization in models and the omission of the intra-variation of PFTs. Modelling studies have also shown that the local climate is highly sensitive to the selection and combination of PFTs. Therefore, a less parameter-dependent approach, of which the results should be robust to the empirical selection of parameters, is critical to address vegetation-climate interaction in climate models.

Based on a process-based plant functioning trade-off scheme developed by Kleidon and Mooney (2000), we have set up a new vegetation model JeDi-BACH and have implemented the new model into the land component of the ICON-Earth System Model (ICON-ESM). The advantage of this new model is to obtain plant distribution as a result of environmental filtering. Plants are represented based on several well-known fundamental functional trade-offs that link the plant functions to abiotic and biotic attributes. For example, plants which partition more biomass to roots could improve their soil-water uptake and thereby reduce the stress from water shortage. Each plant functional aspect is defined by a set of plant-trait parameters that is randomly generated for each plant species. Hence, every parameter set realizes a plant growth strategy with different functional capabilities. Using a large number of randomly generated plant growth strategies, plants are allowed to ‘grow’ everywhere; but the environment will select the survivors. In such a way, plants dynamically adjust to the changing environment and meanwhile influence climate. We have done several simulations of present-day climate with JeDi-BACH and coupled to the atmosphere component of the ICON-ESM to investigate how such an adaptive ecosystem interacts with regional and global climate. Future investigations will focus on non-analogue climates (eg. Eocene with tropical vegetation at high latitudes) where in contrast to PFT-based DGVMs the new model allows vegetation to adjust consistently with climate because of its dynamic selection of plant traits by environmental filtering.

Kleidon, A. and Mooney, H. A.: A global distribution of biodiversity inferred from climatic constraints: Results from a process-based modelling study, Glob. Chang. Biol., 6(5), 507–523, doi:10.1046/j.1365-2486.2000.00332.x, 2000.

 
Mg-K-Fe fluid producing mineral reactions, metasomatism and microfabric development during formation of nodular sillimanite-gneiss in the middle crust
Authors: Engvik Ane K. , Trepmann Claudia A. , Austrheim Håkon
Published: March 2021

The Proterozoic gneisses of the Bamble lithotectonic domain (south Norway) underwent intense scapolitisation caused by K- and Mg-rich fluids and extensive albitisation with formation of numerous ore deposits.

By detailed studies of mineral reaction fabrics we document release of the chemical active Mg, K and Fe-components forming the metasomatic fluid: Breakdown of biotite to muscovite releases K, Mg, Fe, Si and H2O. As reaction products tiny Fe-oxide needles are present in the transforming rock. H2O is reacting with K-feldspar to produce additional amounts of white mica and quartz. During a subsequent reaction muscovite is replaced to sillimanite again releasing quartz and a K-rich fluid. The reactions form the peculiar sillimanite-nodular quartzite, but also well-foliated sillimanite-mica gneiss.

Optical and EBSD microfabric studies reveal a shape preferred orientation for quartz, but despite of a pronounced foliation, quartz does not show a crystallographic preferred orientation. A crystallographic preferred orientation is present for mica and sillimanite. Coarse micas show sutured boundaries to quartz, implying low nucleation rates, no crystallographic or surface-energy control during growth and no obvious crystallographic relationship to quartz.

Our study illustrates the transformation of a quartzofeldspatic lithology into sillimanite-bearing quartzite. The mineral replacement and deformation show ongoing metamorphic reactions during deformation. The microfabric data indicates reaction at non-isostatic stress condition. The deduced mineral replacement reactions document a source of K-, Mg- and Fe-rich metasomatic fluids necessary to cause the pervasive scapolitisation and Fe-deposition in the area. The mineral reactions and deformation produce rocks with a new mineralogy and structure; an increased understanding of these processes is important for the modelling of crustal building and geological history.
Sediment export in marly badland catchments controlled by frost cracking intensity, Draix-Bléone CZO, SE France
Authors: Ariagno Coline , Le Bouteiller Caroline , Van der Beek Peter , Klotz Sébastien
Published: March 2021

At the interface between the lithosphere and the atmosphere, the critical zone records the complex interactions between erosion, climate, geologic substrate and life, and can be directly monitored. The sparsely vegetated, steep marly badland catchments of the Draix-Bléone Critical Zone Observatory (CZO), SE France are characterised by high quantities of exported sediment and rapid morphologic changes. Characterizing and understanding the physical weathering processes in this area are key to predict the temporal variability of regolith production and sediment flux, as well as their evolution under changing climate conditions.

Long data records collected in the Draix-Bléone CZO allow analysing long-term regolith dynamics and climatic control on sediment export. Although widely accepted as the first order control, rainfall variability does not fully explain the observed yearly variability in sediment export, suggesting that regolith production and its controls may contribute to the observed pattern of sediment export. Within the several factors that can influence marls weathering (soil moisture, density, chemical weathering), this study focuses on continuous temperature data, recorded at different locations over multiple years, and aims to highlight the role of frost cracking in regolith production. Several proxies for frost cracking intensity have been calculated from these data and compared to the sediment export anomalies, with careful consideration of field data quality. Our initial results suggest that frost-cracking processes have a significant impact on catchment sediment response and should be taken into account when building a predictive model of sediment export from these catchments under a changing climate.
Defining denudation rate of carbonate rocks using cosmogenic 36Cl in the Taurus Mountain, S-SW Turkey
Authors: Hashemi Khadijeh , Sarıkaya M. Akif , Wilcken Klaus M.
Published: March 2021

Denudation of carbonate terrains occurs by the contribution of both chemical and mechanical weathering. In-situ cosmogenic 36Cl is a robust proxy to quantify the long-term total denudation rate of carbonate rocks. In this study, we defined the steady-state denudation rate of carbonate bedrock using 36Cl for 105-106 years under the temperate Mediterranean to semi-arid climate in and around the Taurus Mountain Range, S-SW Turkey. We collected 13 samples from different lithological units; Jurassic-Cretaceous neritic limestone in the temperate western Taurus, Miocene neritic limestone in the semi-arid Central Taurus, and Mesozoic marbles in the continental part of Central Taurus. The calculated denudation rates range from 28.9 ± 1.4 mm/ka in the Mediterranean coastal range to 1.6 ± 0.1 mm/ka towards northern continental/rain shadow. We compared the denudation rates with a range of parameters such as topographic, climatic, lithologic and mechanical properties of rocks. For almost all samples denudation rate increases with elevation, with two exceptions with the highest rates despite their lower elevations. This high denudation rates could be due to their proximity to the sea. Our results showed that denudation rates decrease with increasing distance from the coast. All denudation rates showed a positive correlation with mean annual precipitation (MAP ~ 400-760 mm) as suggested by other studies worldwide. Annual temperatures (MAT ~ 6-16 °C), however, has a negative correlation with the denudation rates, i.e. the highest denudations occur in the low temperatures (MAT ~ 6-8 °C). The mechanical strength of the rocks was measured with a Schmidt hammer in the field. The high rebound values of Schmidt hammer, indicating the high mechanical strength, correlate with low denudation rates. Nevertheless, the mechanical strength of the carbonate bedrock is not as effective as precipitation or available moisture on denudation rates. This could be shown by two samples close to the Mediterranean which both have high mechanical strength nonetheless show the highest denudation rates. In conclusion, our study suggests that carbonate bedrock denudation in Taurus Mountain correlates with high elevation (~ 1900-2250 m), high precipitation (~ 700-800 mm), low temperatures (~ 6-8 °C) and short distances from the Mediterranean coast.
What drives the growth of earthquake clusters?
Authors: Fischer Tomáš , Hainzl Sebastian , Vlček Josef , Salama Ali
Published: March 2021

Migration of hypocenters is a common attribute of induced injection seismicity and of earthquake swarms, which distinguishes them from aftershock sequences. Spreading of the triggering front is often examined by fitting the time dependence of hypocenter distances from the origin by the pore pressure diffusion model. The earthquake migration patterns however often exhibit not only spreading envelopes, but also fast-growing streaks embedded in the overall migration trends. We review the observed migration patterns and show that in the case of self-driven seismicity, where the new ruptures are triggered at the edge of previous ruptures, it is more suitable to examine the cluster growth as a function of the event index instead of time, which often discloses a continuous linear growth during time periods which appeared strongly discontinuous in the coordinate-time plots.

We propose a model that relates the speed of seismicity spreading to the average rupture area and the effective magnitude of the hypocenter cluster. Application of the model to selected linearly growing clusters of the 2008 West Bohemia swarm gives almost linear increase of the measured total rupture area with the event index, which fits the proposed model. This is confirmed by a self-similar scaling of the average rupture area with the effective magnitude for stress drops ranging from 0.1 to 1 MPa. The relatively small stress drop level indicates the presence of voids along the fault plane and a possible role of aseismic deformation. Further application of the model to seismic swarms from different areas confirms its validity and potential for distinguishing fluid-triggered seismicity.
Anthropogenic land use change and fire history during the Holocene in the Iberian Peninsula
Authors: Sweeney Luke , Vander Linden Marc , Harrison Sandy
Published: March 2021

Anthropogenic land-use change and ecosystem management have a demonstrable impact on modern fire regimes. However, when in time this influence was first felt is still an open question. We investigate whether an anthropogenic signal can be identified in Holocene fire records from the Iberian Peninsula, a region with abundant palaeoenvironmental and archaeological data. We analyse sedimentary charcoal data from 49 sites across the Peninsula covering part or all of the past 12,000 years to construct the fire history for the region. We compare these records to the summed probabilities of radiocarbon-dated archaeological sites, which provides an index for changes in human impact on land use and land cover due to the growth or decrease in human population through time. This reconstruction is based on 8200 radiocarbon dates covering the timespan between12000 and 3500 uncal BP.  Our analyses confirm that the broad trends in fire history are well aligned with the likely impact of climate changes during the Holocene. The charcoal records indicate a rapid increase in fire at the end of the Younger Dryas, a reduction in fire during the middle Holocene as a result of wetter conditions across the Peninsula, and an increase in fire concordant with the increased aridity registered during the interval after 3000 yr BP. However, finer-scale temporal variations are superimposed upon these broadscale changes. Similarly, although the most pronounced change in population reflects population growth associated with the onset of agriculture in the mid-Holocene, the summed probability record of population shows considerable finer-scale temporal variation. In addition to analyses of the temporal correlations between the two data sets, we consider whether there are distinct geographic patterns that could provide additional insights into the relationship between human activities and fire across Iberia.
Energy Export from the Tropical Pacific via the Atmosphere – a Lagrangian Perspective
Authors: Baier Katharina , Stohl Andreas , Mayer Michael , Haimberger Leopold
Published: March 2021

The El Niño-Southern Oscillation (ENSO) is linked with energy exchange between the ocean, atmosphere and space. By using the particle dispersion model FLEXPART the atmospheric energy transport originating from the Tropical Pacific is analysed, with special focus on the connection to the Atlantic Ocean during El Niño. The Lagrangian model was filled homogeneously with five million, globally distributed particles, which were then traced forward in time from 1990 until 2016. Due to the domain-filling option used in FLEXPART, the particles represent the atmospheric mass transport. From this 26 year-long Lagrangian Reanalysis Dataset, particles between 5°S-5°N and 170°W-100°W were selected and followed both forward and backward in time. Therefore, the source regions of the energy and moisture in the Tropical Pacific can be detected, but also where they are further transported. Special focus is placed on the connection to the Atlantic Ocean. By analysing the different forms of energy (potential, - internal, - and latent energy), their transport from the Tropical Pacific into the Atlantic Ocean can be quantified. In addition, the differences between El Niño and La Niña are studied, as well as strong and weak El Niño cases.
Subsidence of the lava flow formed during 2012-2013 Tolbachik fissure eruption: SAR data and thermal model
Authors: Mikhailov Valentin , Volkova Maria , Timoshkina Elena , Shapiro Nikolay , Smirnov Vladimir , Dmitriev Pavel , Babayantz Igor
Published: March 2021

During the Tolbachik fissure eruption which took place from November 27, 2012 to September 15, 2013 a lava flow of area about 45.8 km2 and total lava volume ~0.6 km3 was formed. We applied method of persistent scatterers to the satellite Sentinel-1A SAR images and estimated the rates of displacement of the lava field surface for 2017–2019. The surface mainly subsides along the satellite’s line-of-sight, with the exception of the periphery of the Toludski and Leningradski lava flows, where small uplifts are observed. Assuming that the displacements occur mainly along the vertical, the maximum average displacement rates for the snowless period of 2017–2019 were 285, 249, and 261 mm/year, respectively. On the Leningradski and Toludski lava flows the maximum subsidence was registered in areas with the maximum lava thickness.

To estimate the thermal subsidence of the lava surface we constructed a thermal model of lava cooling. It provides subsidence rate which are generally close to the real one over a significant part of the lava field, but in a number of areas of its central part, the real subsidence values are much higher than the thermal estimates. According to the thermal model when lava thickness exceeds 40 meters, even 5 years after eruption under the solidified surface there can be a hot, ductile layer, which temperature exceeds 2/3 of the melting one. Since on the Leningradski flow, the maximum subsidence is observed in the area of the fissure along which the eruption took place, one could assume that the retreat of lava down the fissure could contribute to the observed displacements of the flow surface. Subsidence can also be associated with compaction of rocks under the weight of the overlying strata. Migration of non-solidified lava under the solidified cover, also can contribute to the observed distribution of displacements - subsidence of the surface of the lava field in the upper part of the slope and a slight uplift at its periphery.

The work was supported partly by the mega-grant program of the Russian Federation Ministry of Science and Education under the project no. 14.W03.31.0033 and partly by the Interdisciplinary Scientific and Educational School of Moscow University «Fundamental and Applied Space Research».
3D Monte-Carlo Model of Europa's Water Plumes
Authors: Vorburger Audrey , Wurz Peter
Published: March 2021

With the pending launches of JUICE and Europa Clipper within the next three years, interest in Europa plumes and the implications they might hold has regained momentum.

In 2014, Roth et al. presented first evidence for Europa plume activity based on Hubble Space Telescope (HST) Space Telescope Imaging Spectograph (STIS) Lyman-alpha and OI 1304 Å line emission observations. The observed line emissions imply two underlying plumic sources, located ~20° apart, exhibiting radial expansions of ~200 km and latitudinal expansions of ~20°, and containing ~2,000 kg of H2O (~1.5 ∙ 1016 H2O/cm2). Since then, several more Europa plume observation attempts were undertaken, though only a hand full proved successful. 

Most importantly, the true nature of the observed plume signature still remains to be determined. Plumes can either originate from the topmost surface layer, from within the ice layer, or from the sub-surface ocean. Depending on the location of origin, the plumes contain information about vastly different zones: If they are surficial, they will contain information about the highly irradiated and highly processed surface, if they originate from the sub-surface ocean, they might hold information on Europa’s potentially life-bearing region.

In this presentation, we present 3D Monte-Carlo model results of three different plume scenarios, two of which originate in Europa’s surface ice layer (near-surface liquid inclusion and diapir) whereas the third originates in the sub-surface ocean (oceanic plume). In this model we trace not only the H2O molecules, but also its dissociation products, i.e., OH, H and O. To compare the plume structures obtained from the Monte-Carlo model to the HST-STIS observations, we include all known relevant Lyman-alpha and OI 1304 Å emission excitation mechanisms in our model. Such a comparison does not only shed more light on the plumes that have already been observed, but will also help targeting plume measurements in the near future, as well as interpreting in situ measurements once such become available.
Physics-based model relating seismic velocity variation to groundwater and pore pressure fluctuation
Authors: Fokker Eldert , Ruigrok Elmer , Hawkins Rhys , Trampert Jeannot
Published: March 2021

Previous studies examining the relationship between the groundwater table and seismic velocities have provided contradictory results, sometimes reporting positive and sometimes negative correlations between seismic velocity and groundwater table changes. Here we introduce a physics-based model relating fluctuation in the groundwater table and the pore pressure to seismic velocity variation through change in effective stress. This model can be used to explain the contradictory results of previous studies and justifies the use of seismic velocity variation for monitoring of the pore pressure and the groundwater table. It further results in a new field method to measure the pressure dependency of the shear modulus. Using data acquired in Groningen, the Netherlands, we demonstrate that measurements of seismic velocity variation can be used to monitor the pore pressure.
Inspiring creativity in science-inspired art and music in the digital world.
Authors: Hanlon Shane
Published: March 2021

The mission of the American Geophysical Union’s Sharing Science program is to provide scientists with the skills, tools, and opportunities they need to share their science with any audience. While we in the program possess the skills and expertise to do this, we also believe that it’s beneficial for artists to learn from, and be inspired by, their peers. To achieve this goal, we created a digital space for science artists to share their work and creative processes.

In 2020, we launched two specials series on our blog: AGU Rocks and Drawn to Geoscience. The purpose of these series was to highlight scientists who write songs and create illustrations about science. We not only wanted to showcase the amazing creative work of science artists but also have them explain their creative and technical processes in as effort to lower the barrier to entry for those who may be interested in pursuing similar creative efforts but don’t know where to start.

By the end of 2020, we received over 40 AGU and Drawn to Geoscience contributions with a queue of posts scheduled for 2021. Because of the huge outpouring of submissions and demonstrated enthusiasm for the content, we are planning to expand this into a hub for all forms of scicomm via art where science artists can learn from, and be inspired by, their peers, and scientists and non-scientists alike can learn about diverse aspects of science in engaging and accessible ways. 
A multi-year drought scenario for western Europe
Authors: Gessner Claudia , Fischer Erich , Beyerle Urs , Knutti Reto
Published: March 2021

During the last decades, Europe has experienced intense dry and hot spells, which seriously impact socio-economic sectors and the ecosystem by shortages of water in the summer season. The occurrence of two exceptional consecutive dry summers 2018/2019 let a multi-year drought become a conceivable scenario. In order to implement adaptation strategies for such a natural hazard, stakeholders raise the questions, how dry and hot a worst-case drought scenario would turn out and how long it would take to fully recover from those climate anomalies?

We address these concerns through the generation of storylines, describing the driest plausible multi-year droughts over western Europe. By repeatedly resampling the occurrence of precipitation in the climate simulation, using 100-member ensembles, we inhibit rainfall and dehydrate the soils in western Europe. These storylines and a millennial climate control simulation are carried out with CESM1.2 under pre-industrial forcing.

In doing so, local precipitation is reduced by 80% and local soil moisture falls far below the 1st percentile of the climatology. Even compared to the present and future climate scenarios, still, the number of dry days is very rare in our drought storyline, i.e. we describe a hazardous but unlikely scenario. Moreover, these storylines are associated with the hottest spring, summer and fall temperatures, but also the coldest winter temperatures. Starting large ensembles from each summer of the multi-year drought scenario, i.e. under exceptional dry initial soil conditions, we find that summertime hot and dry spells have a twenty-fold chance to occur plus their persistence extents by about 1.5 days. After strong precipitation deficits in the summer months, the precipitation increases again. Nevertheless, the local soil moisture does not fully recover within the next year so that the following spring and summer season may be affected by re-occurring droughts, aggravating the damage through water deficits for the vegetation growth and the economy.
Remote sensing approach for the fluvial avulsion processes detection and mapping
Authors: Iacobucci Giulia , Troiani Francesco , Milli Salvatore , Piacentini Daniela , Mazzanti Paolo , Zocchi Marta , Nadali Davide
Published: March 2021

The study of the riverscape dynamic in lowland areas is crucial for reconstructing the morphoevolution of the drainage network, especially where human activities have always been strongly connected to the river system. Not surprisingly, the Lower Mesopotamian Plain (LMP) represents the ideal study area, being a large floodplain where the Tigris and Euphrates rivers with their distributaries deposited a large volume of sediments during the Holocene. Here, a complex drainage pattern, characterized by paleochannels, levees and crevasse splays developed, representing the expression of several fluvial avulsion processes during the time. Indeed, the presence of recent and ancient crevasse splays in a given area suggests frequent seasonal floods, but at the same time, their formation and growth represent, in the LMP, an important process that conditioned the location of several human settlements since the 6th millennium BC. In this area, about 200 examples of active and abandoned crevasse splays, with various sizes, have been recognized exclusively through a remote sensing approach. The scarce elevation ranges of the LMP represent the main challenge in the detection and mapping of the crevasse splays features (i.e., channels, levees and deposits), in addition to the definition of the floodplain extension and the anthropic impact on channel networks.

Therefore, the research aims to integrate multi-sensor remote sensing data such as optical multispectral imagery and digital elevation datasets for improving the detection and mapping of crevasse splays. Landsat 8 imagery is adopted for computing two spectral indices (NDVI and Clay Ratio) and carrying on different supervised classification methods (i.e., Mahalanobis, Maximum Likelihood, Minimum Distance and SAM). Each method has been evaluated through the computation of the confusion matrix, assessing the Overall Accuracy, K coefficient, Producer Accuracy and User Accuracy. Elevation data used in the topographic analysis to determine the local micro-relief geometry are derived from two different global DEMs available at the ground resolution of 1 arcsec (AW3D30 and GDEM2). Topographic analysis has been performed to complete and validate the supervised classification results.

The outputs successfully demonstrate the potential of the integration of multispectral imagery analysis and topographic analysis from DEM for detecting and mapping with a satisfactory detail the avulsion processes and for distinguishing their state of activity. The methodological approach is a promising technique for flood hazard and risk mapping, as well as for monitoring flood dynamics, especially within arid and semi-arid zones where flawless water management is essential for guaranteeing sustainable crops, livestock and avoiding wasting water.
Prognosis of water levels in a moor groundwater system influenced by hydrology and water extraction using an artificial neural network 
Authors: Flaig Sascha , Praditia Timothy , Kissinger Alexander , Lang Ulrich , Oladyshkin Sergey , Nowak Wolfgang
Published: March 2021

In order to prevent possible negative impacts of water abstraction in an ecologically sensitive moor south of Munich (Germany), a “predictive control” scheme is in place. We design an artificial neural network (ANN) to provide predictions of moor water levels and to separate hydrological from anthropogenic effects. As the moor is a dynamic system, we adopt the „Long short-term memory“ architecture.

To find the best LSTM setup, we train, test and compare LSTMs with two different structures: (1) the non-recurrent one-to-one structure, where the series of inputs are accumulated and fed into the LSTM; and (2) the recurrent many-to-many structure, where inputs gradually enter the LSTM (including LSTM forecasts from previous forecast time steps). The outputs of our LSTMs then feed into a readout layer that converts the hidden states into water level predictions. We hypothesize that the recurrent structure is the better structure because it better resembles the typical structure of differential equations for dynamic systems, as they would usually be used for hydro(geo)logical systems. We evaluate the comparison with the mean squared error as test metric, and conclude that the recurrent many-to-many LSTM performs better for the analyzed complex situations. It also produces plausible predictions with reasonable accuracy for seven days prediction horizon.

Furthermore, we analyze the impact of preprocessing meteorological data to evapotranspiration data using typical ETA models. Inserting knowledge into the LSTM in the form of ETA models (rather than implicitly having the LSTM learn the ETA relations) leads to superior prediction results. This finding aligns well with current ideas on physically-inspired machine learning.

As an additional validation step, we investigate whether our ANN is able to correctly identify both anthropogenic and natural influences and their interaction. To this end, we investigate two comparable pumping events under different meteorological conditions. Results indicate that all individual and combined influences of input parameters on water levels can be represented well. The neural networks recognize correctly that the predominant precipitation and lower evapotranspiration during one pumping event leads to a lower decrease of the hydrograph.

To further demonstrate the capability of the trained neural network, scenarios of pumping events are created and simulated.

In conclusion, we show that more robust and accurate predictions of moor water levels can be obtained if available physical knowledge of the modeled system is used to design and train the neural network. The artificial neural network can be a useful instrument to assess the impact of water abstraction by quantifying the anthropogenic influence.
Facilitating reproducible science: a workflow for setting up SUMMA simulations anywhere on the globe
Authors: Knoben Wouter , Gharari Shervan , Clark Martyn
Published: March 2021

Setting up earth system models can be cumbersome and time-consuming. Model-agnostic tasks are typically the same regardless of model used and include definition and delineation of the modeling domain and preprocessing of forcing data and parameter fields. Model-specific tasks include conversion of preprocessed data into model-specific formats and generation of model inputs and run scripts. We present a workflow that includes both model-agnostic and model-specific steps needed to set up the Structure for Unifying Multiple Modeling Alternatives (SUMMA) anywhere on the planet, with the goal of providing a baseline SUMMA set up that can easily be adapted for specific study purposes. The workflow therefore uses open source data with global coverage to derive basin delineations, climatic forcing, and geophysical inputs such as topography, soil and land use parameters. The use of open source data, an open source model and an open source workflow that relies on established software packages results in transparent and reproducible scientific outputs, open to verification and adaptation by the community. The workflow substantially reduces model configuration time for new studies and paves the way for more and stronger scientific contributions in the long term, as it lets the modeler focus on science instead of set up.
High–pressure granulite–facies metamorphism and anatexis of deep continental crust: new insights from the Cenozoic Ailaoshan–Red River shear zone, SE Asia
Authors: Wang Haobo , Cao Shuyun , Neubauer Franz , Li Junyu , Cheng Xuemei , Liu Meixia
Published: March 2021

Studies of crustal anatexis have given valuable insights into the evolution of metamorphism–deformation and the tectonic processes at convergent plate margins during orogeny. The transition of metatexite to diatexite migmatite records crucial information about the tectono–thermal evolution and rheology of the deep crust. Along the Ailao Shan–Red River shear zone, metatexite migmatites, diatexite migmatites and leucogranites are widely distributed within the upper amphibolite and granulite facies zones of the Diancang Shan metamorphic complex. The high–pressure granulite–facies metamorphism with mineral assemblage comprising garnet + kyanite + K–feldspar + plagioclase + biotite + quartz + melt is first recognized from the patch metatexite migmatites in the complex. Detailed petrographic evidence and phase diagram reveal that the migmatite underwent nearly isothermal decompression metamorphism, presenting a clockwise P–T path. The peak metamorphic P–T conditions are constrained by phase diagram at ca. 11 kbar and 810 °C, and the amount of melt generated during heating is up to 18 mol%. The extraction and segregation of melts are evidenced by the presence of leucosomes within migmatites and leucogranite dikes, which record the melt flow network through the crust. Zircons and monazites from migmatites record the ages of the melting episode that began at ca. 36 Ma and lasted to ca. 20 Ma. All these results are in accord with orogenic crust thickening accompanied by pervasive anatexis during the Later Eocene to the early Oligocene in the Ailao Shan–Red River shear zone. Combined with available data related to the other continental–exhumed shear zone, we propose that the crustal anatexis has an important effect on the thermal–state of deep–seated shear zones, is thus controlling the rheological behavior of the lithosphere and plays the essential role in the initial localizing of shearing in the lower crust.
Vulnerability and Importance of Arctic Wetlands as large-scale nature-based solutions for Sustainability in a Changing Climate
Authors: Kåresdotter Elisie , Kalantari Zahra
Published: March 2021

Wetlands as large-scale nature-based solutions (NBS) provide multiple ecosystem services of local, regional, and global importance. Knowledge concerning location and vulnerability of wetlands, specifically in the Arctic, is vital to understand and assess the current status and future potential changes in the Arctic. Using available high-resolution wetland databases together with datasets on soil wetness and soil types, we created the first high-resolution map with full coverage of Arctic wetlands. Arctic wetlands' vulnerability is assessed for the years 2050, 2075, and 2100 by utilizing datasets of permafrost extent and projected mean annual average temperature from HadGEM2-ES climate model outputs for three change scenarios (RCP2.6, 4.5, and 8.5). With approximately 25% of Arctic landmass covered with wetlands and 99% being in permafrost areas, Arctic wetlands are highly vulnerable to changes in all scenarios, apart from RCP2.6 where wetlands remain largely stable. Climate change threatens Arctic wetlands and can impact wetland functions and services. These changes can adversely affect the multiple services this sort of NBS can provide in terms of great social, economic, and environmental benefits to human beings. Consequently, negative changes in Arctic wetland ecosystems can escalate land-use conflicts resulting from natural capital exploitation when new areas become more accessible for use. Limiting changes to Arctic wetlands can help maintain their ecosystem services and limit societal challenges arising from thawing permafrost wetlands, especially for indigenous populations dependent on their ecosystem services. This study highlights areas subject to changes and provides useful information to better plan for a sustainable and social-ecological resilient Arctic.

Keywords: Arctic wetlands, permafrost thaw, regime shift vulnerability, climate projection