bluuebunny/crossref_metadata_2025 huggingface dataset:
­­Joint assimilation of ASCAT backscatter and slope into the ISBA land surface model at ISMN stations over Western Europe
Authors: Shan Xu , Steele-Dunne Susan , Hahn Sebastian , Wagner Wolfgang , Bonan Bertrand , Albergel Clement , Calvet Jean-Christophe , Ku Ou
Published: February 2023

ASCAT normalized backscatter and slope are jointly assimilating into the ISBA-A-gs land surface model (LSM) to constrain plant water dynamics processes. An Extended Kalman filter is used as the data assimilation (DA) algorithm with a trained Deep Neural Network as the observation operator to link the states and the observations (Shan et al., 2022). DA and model open loop (OL) runs are performed on ASCAT grid points (GPIs) containing ISMN stations in Europe and validated using data from 2017 to 2019. Performances of DA and OL are evaluated against ISMN in-situ soil moisture observations in different layers and satellite-based LAI observations from the 1km v2 Copernicus Global Land Service project (CGLS) product.Analysis of DA diagnostics suggests that our DA system is free of bias. Domain median values of innovations, residuals and increments are all around zero. The reduction of standard deviation of residuals compared to innovations shows that DA is effective in reducing uncertainties. Median values of O-A/O-F are close to unity, suggesting the weight given to the ASCAT observables ensures that they provide valuable information to constrain the model. Time series standard deviation of normalized innovations are shown to be around 1 which means our DA system satisfies the Gaussian hypothesis. Regional variations in the mean standard deviation suggests that the performance of the assimilation framework varies somewhat across different land covers.Aggregated across space and time, the improvement in domain median values of ubRMSE and KGE are not statistically significant. However, improvement is observed in some land cover types, and at specific times of year. For example, analysis of the monthly performances in Agricultural grid points shows that DA corrects deeper soil moisture in spring. Results from our previous studies suggest that this may be due to the indirect link between deeper soil water availability and vegetation water status revealed by ASCAT slope. There are also improvements in LAI in fall and winter, suggesting potential values of ASCAT observables in crop senescence. This is consistent with results from Bonan et al. (2014), who found that assimilation of LAI with SSM  could shift the delayed plant phenological cycle simulated by ISBA compared towards real observations (Bonan et al., 2014). In addition, it is important to note that assimilation is performed at the ASCAT resolution scale, while the ISMN provides point-scale soil moisture.Analysis of DA diagnostics as well as performance statistics suggest that the efficacy of ASCAT assimilation is sensitive to the prescribed model and observation errors. Ongoing research is focused on providing realistic quantitative values of both to ensure that the information contained in the ASCAT backscatter and slope can be optimally used. 
A lithospheric magnetic field model to spherical harmonic degree 13
Authors: Thebault Erwan , Hulot Gauthier
Published: February 2023

Detailed mapping of the Earth's magnetic field brings key constraints on the composition, dynamics, and history of the crust. Satellite and near-surface measurements detect different length scales and are complementary. However, direct global inversion of a design matrix built with magnetic field measurements locations of near surface and satellite data is numerically intractable at high spatial resolutions.We apply a procedure developed during the Swarm mission satellite preparation phase to bypass this severe computing issue. We first select the magnetic field measurements during magnetically quiet days of the German CHAMP satellite up to year 2010 and of the ESA Swarm satellites from January 2014 to 31st August 2022. We then build a a complete dataset by combining the selected satellite measurements with the second version of the World Magnetic Anomaly Map; the most globally complete grid of airborne and marine data.We follow a regional approach for the modelling of the full vector, scalar and gradient dataset. We compute a series of spherical cap harmonic models within 700 overlapping spherical caps tiling the Earth’s sphere. This regional strategy allows us to perform linear inverse problems in parallel using robust procedures, to deal with the Backus effect in equatorial regions, and to assess independently each regional model. The complete procedure is described in Thébault, Erwan, et al. "A Spherical Harmonic Model of Earth's Lithospheric Magnetic Field up to Degree 1050." Geophysical Research Letters 48.21 (2021): e2021GL095147).  We finally transform the series of regional models into a unique set of spherical harmonic (SH) Gauss coefficients. This produces the first global model to SH degree 1300. The new model agrees with previous satellite-based models at large wavelengths and fits the CHAMP and Swarm satellite data down to expected noise levels. Further assessment in the geographical and spectral domains show that the model is stable when downward continued to the Earth's surface.
From sedimentation to multiple tectono-thermal events: U/Pb zircon and allanite dating in the Eastern Alps
Authors: Stumpf Sebastian , Skrzypek Etienne , Stüwe Kurt , Iglseder Christoph
Published: February 2023

The affiliation of the Ennstal Phyllite Zone (EPZ) to either the micaschist units of the Koralpe-Wölz nappe system (KW-NS) to its south or to nappes of the “Greywacke Zone” to its north and east is still debated. Due to similarities with phyllites of the “Greywacke Zone” in the north and phyllonitic micaschists in the south, no clear lithological boundary between these units is observable. Petrographic observations suggest a continuous eoalpine metamorphic gradient with no metamorphic gap between the KW-NS and the EPZ. In order to clear this debate and further constrain the tectonic and temporal evolution of these units, we present new LA-MC-ICP-MS U/Pb age dating results for metapelite samples from the EPZ as well as for the adjacent units of the KW-NS.Two samples (EA09 and SP02) from the central EPZ and one sample (SP62) from the northernmost part of the Wölz-Complex of the KW-NS were selected for detrital zircon age dating. The distribution of approximately 150 dates per sample reveals major peaks at the Ediacaran-Cryogenian boundary (624 – 646 Ma), a smaller peak at the Neoproterozoic-Mesoproterozoic boundary (~1000 Ma) followed by a hiatus and a smaller peak in the mid-Paleoproterozoic (~2000 Ma). All samples show similar mid-Paleoproterozoic and Neoproterozoic-Mesoproterozoic peaks. Sample SP62 contains one grain of Cambrian age (523 Ma) and one grain of mid-Ordovician age (460 Ma) whereas the youngest zircons from the EPZ samples yield Ediacaran ages of 629 Ma and 625 Ma. The lack of zircons of Ordovician age in samples EA09 and SP02 indicate an affiliation of the EPZ with the basal units of the “Greywacke Zone”.We also dated metamorphic allanite and REE-bearing epidote rims which are interpreted to form at low pressure and temperature conditions in metapelites. Allanites from the EPZ yield metamorphic ages of 105 ± 3.5 Ma in the northern part of the unit and 279 ± 6 Ma in the southern part. Allanite cores from two micaschist samples from the northern and central Wölz-Complex yield ages of 316 ± 21 Ma and 286 ± 11 Ma. Their respective epidote rims yield eoalpine ages of 98 ± 2 Ma and 96 ± 2 Ma. One micaschist sample from the Rappold-Complex yields ages of 326 ± 9 Ma for the allanite cores and 101 ± 1 Ma for the epidote rims. These ages are interpreted as prograde crystallization of allanite and epidote and give us petrochronological information about three distinct metamorphic events: Variscan, Permian and Eoalpine. By gathering three distinct eoalpine ages within the EPZ and the KW-NS, we can further constrain the metamorphic evolution of the eoalpine lower plate.
Utilizing AI emulators to Model Stratospheric Aerosol Injections and their Effect on Climate
Authors: Agrawal Eshaan , Schroder de Witt Christian
Published: February 2023

With no end to anthropogenic greenhouse gas emissions in sight, policymakers are increasingly debating artificial mechanisms to cool the earth's climate. One such solution is stratospheric atmospheric injections (SAI), a method of solar geoengineering where particles are injected into the stratosphere in order to reflect the sun’s rays and lower global temperatures. Past volcanic events suggest that SAI can lead to fast substantial surface temperature reductions, and it is projected to be economically feasible. Research in simulation, however, suggests that SAI can lead to catastrophic side effects. It is also controversial among politicians and environmentalists because of the numerous challenges it poses geopolitically, environmentally, and for human health. Nevertheless, SAI is increasingly receiving attention from policymakers. In this research project, we use deep reinforcement learning to study if, and by how much, carefully engineered temporally and spatially varying injection strategies can mitigate catastrophic side effects of SAI. To do this, we are using the HadCM3 global circulation model to collect climate system data in response to artificial longitudinal aerosol injections. We then train a neural network emulator on this data, and use it to learn optimal injection strategies under a variety of objectives by alternating model updates with reinforcement learning. We release our dataset and code as a benchmark dataset to improve emulator creation for solar aerosol engineering modeling. 
What role did Tharsis formation during the Noachian/Hesperian period (3.8 – 3.5 Ga) have on the erosional history of Mars?
Authors: Davies Hannah Sophia , Bouley Sylvain , Baratoux David , Braun Jean
Published: February 2023

On Earth, the characteristics of fluvial erosion depends on two main parameters: climate (rain fall) and tectonic history. Mars is a planet that experienced erosion driven by liquid water but its geodynamics are vastly different from Earth’s. Mars therefore represents a unique opportunity to understand how landscape evolution differs on a planet with a “stagnant lid” tectonic regime. The formation of Tharsis dome, a vast volcanic province, during the early history of Mars represented a major magmato-tectonic upheaval for the planet. Over several hundreds of million years, the Tharsis region experienced large scale magmatic intrusions, crustal deformation and effusive volcanism resulting in crustal growth, dynamic uplift and true polar wander (TPW) that accounts for the present location of the Tharsis dome at the equator. This event occurred during a time when Mars had an active water cycle, although the total mass and relative proportion of ice, liquid water and vapor is not well constrained. The uplift and subsequent true polar wander of Mars have affected drainage systems across the planet with many being abandoned or modified due to the variable uplift or subsidence as a lithospheric response to the regional upheaval in the Tharsis region (load on the elastic lithosphere) and TPW. Here we present results from numerical simulations performed using a stream power law algorithm on Mars during the Noachian/Hesperian growth of Tharsis to assess how the patterns of erosion rate are affected by the distribution of atmospheric moisture and flow routing in an attempt to reproduce the observed distribution of valley networks and their geometry. For this, we adapted and used the fully-implicit and O(n)-complexity FastScape algorithm to perform the simulation at the planetary scale. The aims of this work are to quantify the effect of Tharsis dome formation on fluvial systems during the Noachian and early Hesperian, and to establish a first-order erosion rate for this period. This study could help to constrain how much water was cycling on Mars at this time.
Investigating Flux Rope Eruptivity via Time-dependent Data-driven Modelling
Authors: Wagner Andreas , Kilpua Emilia K. J. , Price Daniel J. , Pomoell Jens , Poedts Stefaan , Bourgeois Slava , Kumari Anshu , Daei Farhad , Sarkar Ranadeep
Published: February 2023

Data-driven coronal models are attracting increasing attention for their ability to accurately capture the pre-eruption magnetic field configuration of active regions. However, the degree to which the current modelling techniques are able to provide information on the loss of stability and initial dynamics of the eruptions remains unclear. An interesting avenue for probing this is by employing time-dependent modelling such that the dynamic data-driving is switched-off at a given time. In this study, we investigate what we can learn from this relaxation procedure about the eruption itself and the instability that ultimately triggers it for at least two different active regions. To this effect, we use the time-dependent data-driven magnetofrictional model (TMFM) and perform multiple runs with varying relaxation times (i.e., time instances when the driving is switched off). Furthermore, we use two different physical models to simulate the coronal evolution after this point in time: the standard magnetofrictional method and a zero-beta MHD (magnetohydrodynamics) approach. In case of an eruption being triggered, the detailed evolution is characterised by tracking the associated magnetic flux rope which is extracted from the simulation data with a semi-automatic extraction algorithm. This flux rope detection and tracking procedure makes use of the twist number Tw, as well as the morphological gradient. For a further improvement of the extraction procedure, various mathematical morphology algorithms are performed to accurately extract the flux rope field lines. The properties of the extracted flux ropes are compared against their observational low-coronal manifestation in SDO/AIA data. 
Gravity-constraint salt distribution and migration model in the South Pyrenean Central Salient
Authors: Santolaria Otín Pablo , Ayala Concepción , Clariana Pilar , Soto Ruth , Muñoz Josep Anton , Rubio Félix M. , Martín-León Juliana , Pueyo Emilio L.
Published: February 2023

Upon shortening, salt distribution determines the formation of salients and reentrants in fold-and-thrust belts. Such distribution is controlled by the original sedimentary architecture of the salt basin and subsequent post-sedimentary salt tectonics. In the Southern Pyrenees, the South Pyrenean Central Salient detaches on Triassic evaporites (the regional décollement of the Pyrenees) and stands as a prominent feature bounded, to the north and to the south, by diapiric provinces. Despite its subsurface geometry has been characterized by 2D reflection seismic profiles and exploration wells, an accurate image of the distribution at depth of the Triassic evaporites remains unsolved. In this work, we present an updated observed residual gravity anomaly map of the South Pyrenean Central Salient together with three gravity-validated cross-sections that give structural meaning to gravity anomalies and therefore yields a further interpretation of them helping to interpret those areas lacking seismic images. Middle-Upper Triassic salt accumulations dominate in the western half of the South Pyrenean Central Salient. To the northwest, a prominent accumulation of Triassic evaporites is likely associated with an inherited accumulation predating the Pyrenean orogeny and associated with extensional to gravity-driven salt tectonics during the rift and post-rift stages. To the South, Triassic rocks core salt-detached anticlines. Along the southernmost (and youngest) thrust sheet of the salient, diapirs and evaporite accumulations are associated to an inflated area resulting from the north-coming migration of evaporites during the middle to late stages of the Pyrenean orogeny.
The Direct Effect of Submarine Groundwater Discharge on the Concentration of Dissolved Oxygen in Estuarine and Coastal Waters
Authors: Moore Willard , Joye Samantha , Sibert Ryan , Shiller Alan , Moody Amy , Benitez-Nelson Claudia
Published: February 2023

Submarine groundwater discharge (SGD) is recognized to supply nutrient elements nitrogen and phosphorus to coastal waters. In some cases, these nutrients are essential for biological productivity; in other cases, the nutrients are in excess or change relative proportions such that they impact community structure and/or increase algal blooms. Often overlooked is the role of reducing substances in salty SGD such as H2S, NH4+, CH4, and DOM, which create a direct demand for dissolved oxygen (DO) and lower its concentration in estuarine and coastal waters. We call this SGD-Oxygen Demand or SGD-OD. These reduced substances primarily result from the oxidation of carbon in aquifers and aquicludes by seawater sulfate. Thus, coastal aquifers transitioning from freshwater to seawater due to seawater intrusion are most vulnerable. Saturated seawater DO concentrations are on the order of 200 µM; reducing DO in coastal waters to <150 µM induces biological stress on many organisms; reducing DO to <60 µM (hypoxic conditions) can be deadly. Studies have directly correlated DO depletion with increased SGD off the coast of South Carolina and Mississippi, USA, and in the Yangtze delta, China. These depletions initially affect near-bottom dwelling organisms and may be recognized by sudden fish kills. In this talk we will review a data base of reducing substances in coastal groundwaters and illustrate how the discharge of this water could impact estuaries and coastal waters. We will show additional examples where we hypothesize SGD-OD is occurring in hopes others will have the resources to investigate these areas.  
On localising North Atlantic’s microseism sources using time reversal imaging
Authors: Le Pape Florian , Bean Christopher J. , Vijayan Athira , Fink Mathias
Published: February 2023

The ambient seismic noise is dominated by surface waves associated with ocean microseisms that are defined by a strong acoustic/seismic coupling at the seafloor. The understanding of microseism sources not only benefits seismic passive imaging and monitoring, but can also help track ocean storms using seismic signals recorded on land. Numerical simulations show that heterogeneous seafloor morphologies and structures can significantly affect the propagation of microseism’s surface waves and therefore the accuracy in locating their origin using traditional methods, such as array beamforming. Here, we aim to investigate how the use of time-reversal imaging can help overcome those limitations. The technique has mainly been developed for acoustics but has been applied successfully in seismology for earthquake localisation. Time-reversal imaging consists on back-propagating, through a realistic model, the signal measured at a network of receivers so that it eventually refocuses back at its origin. For this study, simulations are performed using the code SPECFEM3D and a regional 3D acoustic/elastic model of the Irish offshore, with seismic receivers homogeneously distributed along the coast of Ireland. First, methodologies and stations layout are tested with synthetic data generated from forward modelling using different source distributions. Processing approaches for the time-reversed simulation results are investigated in order to optimize the recovery of the original sources. Following those tests, real time windows of seismic noise “events” are then back-propagated into the model with the aim to map the microseism sources associated with local storms in the model area. The results are compared with microseism sources derived from global ocean wave models. Overall, the use of time-reversal imaging for microseism sources localisation looks promising. Although challenging due to the diffuse distribution of sources, there is good potential for developing further our understanding of microseism sources and monitor dominant microseism generation areas in the North Atlantic region with the implementation of a larger model.
Geodetic evidence for compressional interseismic deformation onshore Paliki Peninsula, Cephalonia, Greece
Authors: Tsironi Varvara , Ganas Athanassios , Valkaniotis Sotiris , Kouskouna Vassiliki , Kassaras Ioannis , Sokos Efthimios , Koukouvelas Ioannis
Published: February 2023

We present new geodetic (InSAR) data (ground velocities) combined with GNSS data over the Paliki Peninsula, western Cephalonia, Greece. Paliki Peninsula suffers from strong, frequent earthquakes due to its proximity to the Cephalonia Transform Fault (CTF). The CTF, a 140 km long, east-dipping dextral strike-slip fault, accommodates the relative motion between the Apulian (Africa) and Aegean (Eurasia) lithospheric plates. The most recent earthquakes of Paliki include two events during early 2014 (Ganas et al. 2015); which occurred on 26 January 2014 13:55 UTC (Mw=6.0) and 3 February 2014 03:08 UTC (Mw=5.9), respectively. Long-term monitoring of active faults through InSAR has been successfully applied in many studies so far, not only towards identifying locked or creeping sections, but also to monitor the spatial and temporal patterns of deformation of the surrounding rocks. The processing of InSAR time series analysis was held by the LiCSBAS, an open-source package. To perform an estimate of the velocity of a surface pixel through time based upon a series of displacement data, we apply an SB (small baseline) inversion on the network of interferograms, in particular we applied the N-SBAS method. Then, we transformed the ground velocities of InSAR into Eurasia-fixed reference frame using the available GNSS station velocities. The time series analysis covers the period 2016-2022. The InSAR results demonstrate that active faults onshore Paliki are oriented approximately N-S and slip with rates between 2-5 mm/yr in line-of-sight (LOS) direction. The InSAR results also show that the horizontal component of movement is dominant, therefore supporting initial evidence of the existence of right-lateral strike slip faulting onshore the peninsula. The velocity pattern of the NW part of the peninsula also reveals a possible post-seismic motion along the ruptured plane of the 3 February 2014 earthquake. In addition, the time series analysis has identified other possible active structures (both strike-slip and thrust) onshore the Paliki peninsula and across the gulf of Argostoli that are confirmed by field geological data. The coastal town of Lixouri undergoes uplift (a few mm/yr) as it observed with positive LOS values in both satellite imaging geometries. Through the East-West velocity cross-sections, we determine several velocity discontinuities (block boundaries?) which are possibly bounded by active faults and/or crustal flexure. Overall, our results indicate a complex deformation pattern onshore the Paliki peninsula.
openEO Platform – showcasing a federated, accessible platform for reproducible large-scale Earth Observation analysis
Authors: Schumacher Benjamin , Griffiths Patrick , Pebesma Edzer , Dries Jeroen , Jacob Alexander , Thiex Daniel , Mohr Matthias , Briese Christian
Published: February 2023

openEO Platform holds a large amount of free and open as well as commercial Earth Observation (EO) data which can be accessed and analysed with openEO, an open API that enables cloud computing and EO data access in a unified and reproducible way. Additionally, client libraries are available in R, Python and Javascript. A JupterLab environment and the Web Editor, a graphical interface, allow a direct and interactive development of processing workflows. The platform is developed with a strong user focus and various use cases have been implemented to illustrate the platform capabilities. Currently, three federated backends support the analysis of EO data from pixel to continental scale.  The use cases implemented during the platform’s main development phase include a dynamic landcover mapping, an on-demand analysis-ready-data creation for Sentinel-1 GRD, Sentinel-2 MSI and Landsat data, time series-based forest dynamics analysis with prediction functionalities, feature engineering for crop type mapping and large-scale fractional canopy mapping. Additionally, three new use cases are being developed by platform users. These include large scale vessel detection based on Sentinel-1 and Sentinel-2 data, surface water indicators using the ESA World Water toolbox for a user-defined area of interest and monitoring of air quality parameters using Sentinel-5P data. The future evolution of openEO Platform in terms of data availability and processing capabilities closely linked to community requirements, facilitated by feature requests from users who design their workflows for environmental monitoring and reproducible research purposes. This presentation provides an overview of the completed use cases, the newly added functionalities such as user code sharing, and user interface updates based on the new use cases and user requests. openEO Platform exemplifies how the processing and analysing large amounts of EO data to meaningful information products is becoming easier and largely compliant with FAIR data principles supporting the EO community at large. 
The role of an interactive methane cycle in climate sensitivity and climate feedbacks
Authors: O'Connor Fiona , Folberth Gerd , Gedney Nicola , Jones Chris
Published: February 2023

Despite methane’s importance as a greenhouse gas, the Earth System Models that contributed to Phase 6 of the Coupled Model Intercomparison Project (CMIP6) typically prescribe surface methane concentrations - following either historical observations or specified future shared socioeconomic pathways. Here, we make use of novel methane emissions-driven capability in the UK’s Earth System Model to explore the role of an interactive methane cycle, including wetland emissions, on the model’s equilibrium climate sensitivity and its transient climate response to changes in carbon dioxide concentration.The climate response to external forcings is strongly influenced by climate feedbacks and with the inclusion of interactive methane in Earth System Models, it becomes important to understand the effects of changing carbon dioxide and meteorology on wetland emissions.  This work re-evaluates the CMIP6 assessment of the methane wetland emissions feedback in UKESM1 by taking account of wetland emissions’ sensitivity to both meteorology and carbon dioxide. This presentation demonstrates the need for including interactive methane in Earth System Models. By allowing changes in natural methane emissions to influence methane concentrations and climate, this novel capability enables scientists to determine the consequences of methane emission reduction policies or climate feedbacks on natural methane sources towards meeting global climate as well as global air quality targets.
Hierarchical clustering of Sentinel-1 SAR data for soil moisture estimation at the field scale
Authors: Graldi Giulia , Vitti Alfonso
Published: February 2023

Superficial soil moisture is a key hydrological variable playing a main role in the fluxes of water and heat between land and atmosphere. Its spatial and temporal variations are indeed crucial for applications such as environmental modelling and agricultural management. Soil moisture direct measurements lack spatial representativeness, while soil moisture spatialized information could be derived from satellite data acquired by active microwave sensors. In recent years, missions such as ESA’s (European Space Agency) Sentinel-1 SAR (Synthetic Aperture Radar) mission has provided open data at high resolution (up to 20 m) and temporal frequency (6 days at the equator latitudes before December 2021).In the proposed work, high resolution data of Sentinel-1 are analyzed on an agricultural area at a resolution of 20 m over a 4 year period. In particular, it is proposed a hierarchical approach for detecting time and space domains where coherently apply a Change Detection method for retrieving soil moisture from the co-polarized band of Sentinel-1 data. The study is conducted at the field scale. Given the agricultural land use of the study area, the total SAR backscattered signal is modelled as the sum of vegetation and attenuated soil contributions.At first, a classification for masking out the sub-areas dominated by a volumetric response due to vegetation is performed. For doing this, the adaptive thresholding method proposed by Satalino et al., 2014 [1] is performed on proper SAR parameters, such as the VH band, the RVI (Radar Vegetation Index) adapted to Sentinel-1 data [2], and the cross-polarized Interferometric Coherence. The resulting classifications derived from the different parameters are then compared. When working on an agricultural area at the resolution of 20 m, the effects of the soil roughness changes on the backscattering coefficient could not be neglected. For considering them, since no soil roughness data are available on the study area, a time series analysis for detecting steep changes in the co-polarized band is performed. By doing this, it is expected to detect temporal clusters in which no soil roughness variations occur, and thus where a CD method can be applied. The results of the latter classification may be compared with an optical roughness index.REFERENCES[1] G. Satalino, A. Balenzano, F. Mattia and M. W. J. Davidson, "C-Band SAR Data for Mapping Crops Dominated by Surface or Volume Scattering," in IEEE Geoscience and Remote Sensing Letters, vol. 11, no. 2, pp. 384-388, Feb. 2014, doi: 10.1109/LGRS.2013.2263034.[2] M. Trudel, F. Charbonneau, R. Leconte, “Using RADARSAT-2 polarimetric and ENVISAT-ASAR dual-polarization data for estimating soil moisture over agricultural fields”. Canadian Journal of Remote Sensing 2012, 38, 514–527.
Can Bias correction Techniques Improve Remote Sensing-based Rainfall Estimates in a Semi-Arid Context: Case of the Oum Er-Rbia River Basin in Morocco
Authors: Ouatiki Hamza , Boudhar Abdelghani , Chehbouni Abdelghani
Published: February 2023

In semi-arid contexts, the strong spatiotemporal fluctuation of rainfall and the sparsity of the rain gauge (RG) measurement networks are the main limitations for water resources management. Freely available satellite-based rainfall estimates can be a potential source of information to cop data limitations over poorly gauged regions. Thus, the main aim of this work was to investigate how eight Spatial Rainfall Products (SRP, ARC-2, CHIRPSp25, CHIRPSp5, CMORPH-CRT, GPM-IMERG, PERSIANN-CDR, RFE-2, and TRMM-3B42) can be able to reproduce the observed monthly rainfall over a semi-arid context. The SRP estimates were directly evaluated against the RG observations. Then, bias correction techniques were used to account for the bias in the SRPs. The results indicated that the SRPs poorly correlate with the daily rainfall patterns (with Pearson Correlation Coefficients (PCCs) mostly below 0.5) but agreed with the monthly observations. The agreement was stronger over the lowlands than over the mountainous region. Overall, out of all the considered SRPs, IMERG (with a short-term record) and PERSIANN (with a long-term record) performed the best. Still, the monthly SRP estimates were significantly biased as the large rainfall totals were frequently underestimated. However, when the bias correction was applied remarkable improvement in the SRP’s performance was observed. The different adopted correction techniques yielded close results, with a slight prevalence of the Cumulative Distribution Function (CDF) over the Linear Scaling (LS), and Simple Linear Regression (SLR) techniques. Still, to reliably adjust the bias in the SRP estimates, LS and SLR should be preferred over the CDF technique, as they demonstrated more spatially consistent performance after validation.
Organic carbon stabilisation mechanisms in estuarine marsh soils: Effect of salinity and flooding frequency
Authors: Neiske Friederike , Becker Joscha N. , Seedtke Maria , Schwarze Daniel , Eschenbach Annette
Published: February 2023

The capability of coastal wetland soils to store large amounts of organic carbon (OC) has been increasingly recognised. Stabilisation mechanisms (e.g. aggregation or mineral association) and stability of organic matter (OM) (recalcitrant vs. labile) are important features for the long-term storage of soil organic carbon (SOC). In estuarine marshes, SOC storage is dominated by a complex and dynamic interaction of abiotic conditions such as tidal inundation or changes in salinity. However, little is known on OC stabilisation and stability in these transitional ecosystems and how they are affected by system-specific characteristics. Therefore, our aim was to assess the effect of flooding and salinity on (i) OC stabilisation by aggregation and mineral association and (ii) the stability of the OC pool in estuarine marsh soils.We analysed topsoil (0 – 10 cm) and subsoil (10 – 30 cm) samples from 9 marsh zones along the salinity gradient (salt, brackish and freshwater) and flooding gradient (pioneer zone, low and high marsh) of the Elbe Estuary for their SOC contents, OC stabilisation mechanisms (density fractionation), OC stability (incubation with one- and two-compartment model fits) and dissolved organic carbon (DOC) concentrations.Total SOC contents were highest in the freshwater marsh and decreased towards topsoils with higher salinity. Flooding frequency had no uniform effect on SOC contents: While there was a positive tendency with decreasing flooding frequency, subsoils of the freshwater marsh showed the opposite trend. Total SOC contents were positively correlated with mineral-associated OC (CMAOM) and pedogenically unprotected particulate OM (CfPOM). The highest proportion of CMAOM was found in topsoils of freshwater marshes and it decreased towards higher salinities in topsoils of high marshes and pioneer zones. The OM protection by aggregation (CoPOM) increased in topsoils of high marshes. The proportion of CfPOM was less directly affected by salinity and flooding than by the CN ratio of the aboveground biomass (CNlitter). Furthermore, CfPOM correlated positively with the potential mineralisable C (Cpot) and labile C (Clabile) and negatively with the recalcitrant C pool (Crecalcitrant) that were derived from the one- and two-compartment models. Labile C, Cpot and Crecalcitrant were also strongly influenced by CNlitter. Moreover, Crecalcitrant was linked to the proportion of CMAOM. Concentrations of DOC increased with total SOC and Cpot but decreased with CoPOM.We conclude that SOC stabilisation in the Elbe Estuary is mainly related to mineral association of OM. With increasing terrestrial influence, physical protection in aggregates becomes more important. Besides these pedogenic stabilisation mechanisms, recalcitrance is strongly determined by vegetation characteristics.
Using the CoCo metric of relative structural complexity of major plate-boundary fault networks to explore potentially time-variable fault loading rates on major strike-slip faults
Authors: Gauriau Judith , Dolan James
Published: February 2023

The Coefficient of Complexity (CoCo) is a metric that quantifies the relative structural complexity of the fault system surrounding a specific study site on a primary fault extending through the system. Specifically, the CoCo metric has been used successfully to correlate the relative constancy or non-constancy of incremental slip rates on major strike-slip faults with the proximity, number, and slip rates of other neighboring active faults within a given radius of observation. Interestingly, our analysis shows that faults that extend through more structurally complex plate-boundary fault systems are characterized by more temporally variable slip behavior than faults that are embedded within simpler settings. Complex stress interactions within structurally complicated tectonic networks, as well as possible temporal changes in fault strength and kinematic interactions amongst mechanically complementary faults, likely explain these different behaviors. The CoCo metric thus not only provides a potential means for better evaluating the future behavior of large plate-boundary faults in the absence of well-documented incremental slip-rate behavior, but also can be used to differentiate faults that typically slip at a constant rate from the ones which do not. Using these results, we explore the relationship between incremental fault slip rates averaged over both short and large displacements on major strike-slip faults and geodetic estimates of strain accumulation rate on faults with different CoCo values. As might be anticipated, our analysis shows that the relatively constant slip rates on faults embedded within structurally simple strike-slip tectonic networks (i.e., low-CoCo faults) generally match rates of elastic strain accumulation of the faults’ shear zones, as measured by geodetic slip-deficit rates. In marked contrast, geodetic slip-deficit rates for faults embedded within structurally complex fault systems (high-CoCo faults) are less consistent with geological rates, whether averaged over short or large displacement scales, indicating significant variations in strain-accumulation rate on high-CoCo faults. We use these data to suggest possible patterns of geodetic-to-geologic rate ratios that may be indicative of the likely near-future behavior of the fault in question.
Transient rheology of feldspar
Authors: Masuti Sagar , Rybacki Erik
Published: February 2023

Transient creep of the lower crustal minerals such as feldspar is important to explain postseismic deformation following a large continental earthquake. However, transient creep of feldspar is poorly understood and the flow law parameters are unknown so far. Therefore, we performed constant strain rate deformation experiments on synthetic fine-grained anorthite aggregates under wet conditions using a Paterson-type gas deformation apparatus. We conducted tests at temperatures from 1000 ºC to 1200 ºC and confining pressure of 400 MPa. Typical strain rates in our experiments were 1x10-4 s-1, 2.5x10-4 s-1, 5x10-4 s-1, and 7.5x10-4 s-1, including some strain rate stepping experiments. In general, the transient creep accounted for 6-8% of the total strain (~10-15%), which is high compared to 2-3 % transient deformation observed in previous experiments on anorthite, quartz, and olivine aggregates. Inspection of the microstructures of deformed samples using transmission electron microscopy reveal dislocation activity and antiphase domain boundaries. Analysis of steady-state creep data indicates that the samples were deformed at the boundary between diffusion and dislocation creep with a power law stress exponent of ~1.4 and an activation energy of 272 kJ/mol. Because a constitutive equation for transient creep of feldspar is not well established, we estimated transient creep flow law parameters using inter-granular and intra-granular models. In the intergranular model for a polycrystalline aggregate, where grains are randomly oriented,  it is assumed that low strain (i.e., transient creep) is accommodated by individual grains with soft/easy slip orientation and high strain (steady-state creep) is accommodated by grains with hard/strong slip orientation. In contrast, in the intra-granular model, both transient creep and steady-state deformation are dominated by intragranular processes, such as long-range elastic interactions of dislocations. In the intragranular approach, we find that the full stress vs. strain curve (i.e., including transient and steady-state creep) can be modelled using a stress exponent of ~1.5 and an activation energy of ~200 kJ/mol. Applying the intergranular model, we get a stress exponent of ~3 and an activation energy of ~130 kJ/mol for transient creep of anorthite aggregates. Extrapolated to natural strain rates, these two approaches will have different implications in modelling postseismic deformation.
The temperature response of photosystem II quantum yield is an important driver of leaf photosynthesis: a review and data synthesis
Authors: Posch Bradley , Smith Nicholas
Published: February 2023

Photosystem II quantum yield (φPSII) measures the efficiency with which photosystem II converts absorbed light to photochemistry, and thus variation in φPSII directly affects leaf CO2 assimilation. Given the sensitivity of photosystem II to temperature stress, increasing our understanding of the φPSII temperature response could improve model estimates of terrestrial carbon cycling in an increasingly warm and erratic climate. We reviewed the literature to establish what is known of the φPSII temperature response and highlighted potential underlying physiological and molecular mechanisms. We then used φPSII temperature response data collated from our review to generate a new and improved temperature response function for φPSII. After examining how a subset of land surface models currently represent φPSII and its temperature response, we incorporated our new temperature response function into the Farquhar, von Caemmerer, and Berry C3 photosynthesis model. The model output showed that RuBP-limited photosynthesis is most affected by the φPSII temperature response as leaf temperatures increase or decrease further from the optimum temperature of φPSII. In addition to providing a new φPSII temperature response function, we also highlight key unanswered questions surrounding the φPSII temperature response that, if addressed, could bolster efforts to predict the effects of temperature on photosynthesis.
Using Docker in environmental research
Authors: Dolich Alexander , Mälicke Mirko , Manoj J Ashish , Wienhöfer Jan , Zehe Erwin
Published: February 2023

The virtual research environment V-FOR-WaTer provides functionalities to store and access hydrological and other environmental data from various sources and disciplines. We propose a framework to run containerized tools within the V-FOR-WaTer toolbox, that is intended to solve the problem of combining software or scripts developed in different programming languages.The framework is used to manage Docker containers, which can contain software like tools for data analysis or environmental modeling. Alongside the well-known advantages of containerization, such as development speed and efficiency, isolation from the local system, dependency management and portability, the usage of containers also ensures a high degree of reproducibility.Given a scientific context, containers are especially useful to combine scripts in different languages following different development paradigms. To do so, we developed a framework-agnostic container specification which standardizes inputs and outputs from and to containers to ease the development of new tools. As of now we also provide templates for tools developed in Python, R, Octave and NodeJS.We present an exemplary workflow for the CATFLOW hydrological model. Data from the V-FOR-WaTer environment is loaded using a Python tool and preprocessed with an existing R tool. After running the FORTRAN model, existing tools in Python, R and MATLAB are used for analysis and presentation of results. When executing the workflow, the user does not need to be familiar with the different programming languages of individual tools, since the containerized tools are self-contained by definition.
The Open Datacube Federation
Authors: Baumann Peter
Published: February 2023

Datacubes are acknowledged as a cornerstone for analysis-ready data as they allow more intuitive, human-centric services. In the GAIA-X EO Expert Group, a subgroup of the GAIA-X Geoinformation Working Group, datacube federations are one of the use cases investigated, specifically: the EarthServer initiative which has set out to materialize the vision of a single integrated, homogenized, location-transparent datacube pool. It bridges a seeming contradiction: a decentralized approach of independent data providers - with heterogeneous offerings, paid as well as free - versus a single, common pool of datacubes where users do not need to know where data sit inorder to access, analyse, mix, and match them. In analogy to the term “server-less” such a federation might be called “datacenter-less” as users do not need to know the concrete data location any longer. Among the service parameters achieved are: - zero-coding, human-oriented space/time analytics;- datacubes uniformly offered through the OGC/ISO/INSPIRE datacube service standards, enabling a wide range of 3rd-party clients with seamless access, such as python xarray, numpy arrays, OpenLayers, Leaflet, NASA WebWorldWind, Microsoft Cesium, QGIS, ArcGIS, and others more;- Server-side extensibility for integrating any 3rd-party code into the service orchestration, such as ML models;- transparent distributed data fusion;- no single point of failure;- seamless offering of both free and paid data and services;- administrator-less continuous growth of datacubes over time, allowing data centers to join the service without assigning dedicated staff resources;- Fine-grain access control, down to single-pixel granularity. The large, continuously growing EarthServer federation (the latest member joining was the Taiwan National Supercomputing Center) is boosted by rasdaman, the pioneer datacube engine whose query language in 2019 has been adopted as the SQL datacube extension. Being the official INSPIRE Good Practice rasdaman effectively integrates Copernicus and INSPIRE seamlessly, paving the way for mapping agencies joining the federation. The aggressive growth of the EarthServer federation is ongoing; a line-up of datacenters has expressed interest, and the charter for governance is being finalized. As of today, EarthServer offers a critical mass of 140+ of Petabytes of multi-dimensional raster data, including 2D DEMs, 3-D satellite image timeseries, and 4-D atmospheric data. Members include several DIAS European Copernicus archives, leading supercomputing research centers, as well as a series of specialized services offering high-level marine, land use, and atmospheric products. All data are accessible with zero coding, in particular: without the need to know python, and strictly standards compliant. Virtual Coverages allow users to see single datacubes even where the underlying data are heterogeneous. In our talk we present the federation rationales and opportunities and show a broad range of real-life distributed data fusion examples.