bluuebunny/crossref_metadata_2025 huggingface dataset:
Imaging the upper crust in the eastern Pyrenees with ambient seismic noise
Authors: Ventosa Sergi , Schimmel Martin , Díaz Jordi , Ruiz Mario
Published: February 2023

We present here a 3D shear-velocity regional model of the eastern Pyrenees centered at the Cerdanya Basin using seismic ambient noise to image structure of the Iberian and Eurasian uppermost crust. In the context of the SANIMS project, we deployed a network of 24 broadband seismic stations that complement existing permanent stations from the CA, ES and FR networks and previous temporal deployments from the OROGEN project, and aside, a high-density short-period seismic network focused on the study the Cerdanya Basin. For the regional study, we use the broadband dataset to compute symmetric cross-correlations of the seismic noise using the wavelet phase cross-correlation and the time-scale phase weighted stack, then estimate the phase and group velocity of Rayleigh waves between 1.5 – 7 s and 1.5 – 5 s, respectively. Afterwards, we build a 3D S-wave velocity model from path-average velocities in two steps: regionalization and pointwise depth inversion. In the regionalization step, we build velocity maps from the dispersion curves measured using the fast marching method on the forward problem and a hybrid l1 – l2 norm criterion on the inversion to enforce robustness to outliers. In the depth inversion step, we apply transdimensional inference to explore for S-wave velocity profiles with an unknown number of layers of constant velocity and the noise variance of the Rayleigh phase and group velocity maps using a least-square misfit function. The best models show a top low-velocity layer 2 – 3 km thick followed by distinct velocity profiles to the North and to the South, corresponding to the expected differences between the Iberian and Eurasian plates. To the South we observe two layers with a boundary at 6 – 7 km depth and velocities of about 3.2 and 3.5 km/s respectively, while to the North velocities are generally lower, increase much less with depth and there is no clear boundary.
Was the 4.2 ka event unusual in context of global Holocene climate variability?
Authors: McKay Nicholas , Kaufman Darrell , Arcusa Stéphanie , Kolus Hannah
Published: February 2023

Abrupt climate changes are commonly observed between 4500 and 4000 years ago, and particular attention has been paid to the “4.2 ka event”, which now serves as a stratigraphic marker to subdivide the mid and late Holocene globally. However, proxy climate records are commonly marked by large, and often abrupt, changes in temperature and moisture throughout the Holocene, and it remains unclear how abrupt change in the mid-Holocene compares to changes throughout the epoch. Here, we assess how regional and global temperature and moisture changes between 4.5 and 4.0 ka compare with other major climate events across the Holocene, in particular the 8.2 ka event. To conduct this analysis objectively, we assess more than a 1000 previously published paleoclimate datasets that span all continents and oceans and include a wide variety of archive and proxy types. All of the data are open access, and the analyses were conducted using the open-source “Abrupt Change Toolkit in R (actR)” software package to determine the timing and significance of multiple types of abrupt change. These include excursion events (significant short-term deviations from the mean state), regime change events (significant rapid shifts in millennial-scale means) and trend change events (significant changes in the long-term trend). We detect multiple significant abrupt change events throughout the Holocene, and therefore evaluate the spatiotemporal significance of events against a null hypothesis of observed background variability. Events at 8.2 ka stand out as large spatiotemporally coherent excursions of temperature and moisture centered in the North Atlantic and globally significant. In contrast, although we detect multiple types of abrupt change in moisture and temperature during the between 4.5 and 4.0 ka, the event does not significantly exceed the expectation of occurrence from our robust null model nor stand out as a regionally coherent anomaly. These results suggest that local abrupt changes are common throughout the Holocene; many of these are regionally coherent, but few are hemispheric or global in extent.
End-of-century heat and drought stress is approaching Europe swiftly
Authors: Suarez-Gutierrez Laura , Müller Wolfgang A. , Marotzke Jochem
Published: February 2023

Extreme heat and drought levels typical of an end-of-century climate could occur soon, and repeatedly. Despite the European climate being potentially prone to multi-year successive extremes due to the influence of the North Atlantic variability on multi-year timescales, it remains unclear how the likelihood of such successive extremes changes under warming, how early could they reach end-of-century levels, and how this is affected by internal climate variability. We use the MPI Grand Ensemble to perform a systematic assessment of how soon different forms of highly impactful, end-of-century single and compound heat and drought stress could occur over Europe, and the role that the decadal variability in the North Atlantic plays in this outcome. Our ultimate goal is to determine how worst-case successive and compounding heat and drought stress accumulates to produce the most extreme decades, and how soon into the near future such heat and drought loaded decades could bring a taste of the end-of-the-century reality. We find that even under moderate warming, end-of-century heat and drought levels virtually impossible 20 years ago reach 1-in-10 likelihoods as early as by the 2030s. By 2050-2075, single and compound end-of-century extremes occurring unprecedentedly for two successive years exceed 1-in-10 likelihoods; while Europe-wide 5-year megadroughts reach non-negligble odds. Moreover, our results show that the range of all plausible conditions that we may come to experience under the same global warming levels is growing wider by the decade. The range of potential heat and drought stress accumulated over a whole decade increases to the point that experiencing heat and drought loaded decades typical of an end-of-century climate could become a reality in Europe as early as 2040, and this is highly influenced by the state of the North Atlantic. Under a concurrent warm North Atlantic state, exceeding end-of-century single and compound heat and drought stress during decades starting as early as in 2030 becomes twice as likely.    
The influence of strong ground motion intensity measures on earthquake induced landslide susceptibility estimates
Authors: Bloom Colin , Stahl Timothy , Massey Chris , Howell Andrew , Singeisen Corinne
Published: February 2023

Strong ground motion intensity measures, for example Peak Ground Acceleration (PGA) or Peak Ground Velocity (PGV), are important dynamic features, or predictive variables, in most regional earthquake induced landslide susceptibility models. Despite global reliance on these ground motion intensity measures, little work has been done to evaluate how dynamic feature selection, and underlying ground motion models, influence the predictive performance of landslide susceptibility models. Here, we conduct a feature sensitivity analysis, training a suite of 131 comparative logistic regression models on the distribution of landslides from the 2016 Mw 7.8 Kaikōura earthquake on the South Island of New Zealand. This analysis uses a combination of common susceptibility features (e.g., slope, curvature), distance to a surface fault rupture (both a susceptibility and dynamic feature), and 9 ground motion intensity measures (PGA, PGV, Arias Intensity, PSA - Peak Spectral Acceleration at 0.3, 1.0, 3.0, and 10.0 seconds, MMI - Modified Mercalli Intensity, and Duration of Shaking) derived from 4 published ground motion models for the Kaikōura earthquake. Ground motion is highly correlated with distance to a surface fault rupture (a Pearson R2 as high as 0.86). Models trained using both distance to surface fault rupture and a ground motion intensity measure produce high model performance but are overfit to the Kaikōura landslide distribution with negative model coefficients for most ground motion intensity measures. Excluding distance to a surface fault rupture still produces high model performance (less than a 0.04 drop in Model AUC) when including the most predictive ground motion intensity estimates (typically MMI, PSA at a period of 0.3 seconds, PGA, or PGV from the USGS ShakeMap) and results in more explainable, and likely more applicable, model coefficients. Although MMI and PSA at a period of 0.3 seconds (3.3 Hz) appear to be good predictors of the landslide distribution from the Kaikōura earthquake, MMI can be influenced by the availability of felt reports and the frequency of shaking can vary in different earthquakes. PGA and PGV provide acceptable model performance for the Kaikōura landslide distribution and are likely more applicable to other events. Highly variable performance is observed when applying the same ground motion intensity measures from different published ground motion models. The choice of ground motion model may, therefore, introduce a high degree of uncertainty into the landslide susceptibility analysis that remains relatively underappreciated in most studies. Additional recorded strong motion data will likely be required to further improve ground motion models, and thereby landslide susceptibility models, for future events.
Studying interactions between low clouds and wind profiles using ALADIN/AEOLUS data
Authors: Titus Zacharie , Chepfer Hélène
Published: February 2023

Wind profiles in the lower troposphere influence the processes driving cloud formation and dissipation. For example, dendritic cumulus and linear sheets formations are governed by different factors including wind direction and velocity. Trade winds and local dynamic processes influence the formation of cumulus and stratocumulus.Using multiple case studies where the ALADIN lidar observes the different cloud patterns mentioned above, we will see how AEOLUS retrieves winds and clouds and what are the links between them. This study will be backed by visible MODIS observations and Calipso-GOCCP data to confirm the presence of clouds and their types. The focus will be around the JATAC area (Cape Verde, June to September 2021 and 2022), especially in the boundary layer, where our knowledge about the interactions between the wind and clouds are yet to be improved.
Chances and risks of aquifer thermal energy storage (ATES) systems
Authors: Blum Philipp , Menberg Kathrin , Fleuchaus Paul , Schüppler Simon , Stemmle Ruben , Barth Florian , Bayer Peter
Published: February 2023

Decarbonising the heating and cooling sector is crucial for reducing our global CO2 emissions. One promising option for environmental friendly energy supply in buildings is the use of shallow geothermal energy (SGE) (< 400 m depth) such as ground source heat pump (GSHP), groundwater heat pump (GWHP) and tunnel geothermal systems. In addition, renewable energy sources such as wind and solar are typically intermittent in nature, which is why they are characterized by an abundant but limited instantaneous availability. Peak time shaving and shifting by thermal energy storage are therefore considered as a key to the transition of the heating and cooling sector from fossil-based to zero-carbon. To balance these temporal variations in the availability and demand, Underground Thermal Energy Storage (UTES) systems could be used. In particular, Aquifer Thermal Energy Storage (ATES) systems are characterized by high storage capacities and low storage costs and is, therefore, drawing growing attention worldwide. However, only little is known about global application and distribution of ATES systems. Hence, this talk will provide an overview of the present and future potential of ATES systems including the chances and risks associated with such systems, which can play an important part in achieving our ambiguous climate targets.
Financial benefits from the implementation of nature-based solutions in the settlements – a case study on a catchment of Lake Velence
Authors: Kalman Attila , Bene Katalin
Published: February 2023

In recent years, the changing weather patterns caused by climate change have already impacted the population, but in 2022, these weather extremes surpassed the ones of previous years. Severe droughts across Europe posed significant challenges, primarily through water scarcity and caused severe (security of supply and economic) damages to different societal sectors. Drier summers and warmer, snow-less winters significantly change the water cycle and thus the amount of naturally retained rainwater on site. A long-term, sustainable solution is the widespread implementation of nature-based solutions.The Lake Velence watershed in Hungary has been showing signs of drying up for years. To implement nature-based solutions, the catchment's natural features, the stakeholders' general requirements, the economic opportunities, and possible benefits must be incorporated. Small- and large-scale agricultural activities face a growing deficit in irrigation water, while the surrounding settlements of Lake Velence can collect a significant amount rainwater. The research focuses on the potential amount of rainwater that can be collected in the selected hilly settlements, it’s uses, and its ability to generate additional income. We evaluated the costs and benefits of implementing or non-implementing nature-based solutions based on the extent of rainwater usage. Using basic calculations of the area's present and possible future cultivation/agricultural activities, we examined the impacts of blue-green infrastructures on local GDP through a lost profit versus available surplus income comparison.
Turning standalone seismometers into strainmeters using tidal strain and ambient noise ‒ a feasibility study
Authors: Müller Jozef , Eulenfeld Tom , Wegler Ulrich
Published: February 2023

Solid Earth is subjected to nanostrain tidal deformations caused by gravitational attraction of the Moon and Sun. This causes periodic deformations of imperceptible fractures in the shallow rock that likely result into subtle variations of seismic velocities. It is possible to theoretically model the gravitational tidal deformations while the seismic velocities can be estimated, e.g., using ambient noise recordings processed with passive image interferometry. Combining these two pieces of information could allow for in-situ assessment of bedrock properties beneath seismic stations. In this study, we tried to accomplish this task using 18 standalone seismic stations (i.e., no array) from a network of the Integrated Plate Boundary Observatory Chile, complemented by several others in Europe and North America. The velocity changes were mostly estimated for frequencies of 1-4 and 4-7 Hz, using hourly Green's functions acquired after temporal stacking. Analysed coda lapse time windows of the Green's functions were 1-6, 5-10 and 8-13 seconds. Tide-related velocity changes were observed (mostly the M2 component). However, our results show that observability of such tide-related velocity variations seems to be strongly related to the station proximity to oceanic coastlines. This raises reasonable doubt about the required solid Earth tides origin of the observed tidal signals.
Measuring the Sensitivity and Stability of Vegetation in Response to the Hydroclimate Across East Africa with an Empirical Dynamic Modeling Approach
Authors: Green Rachel , Caylor Kelly
Published: February 2023

Expanding access to remotely sensed Earth observations provides us with an opportunity to examine the underlying spatiotemporal coupling between vegetation, both natural and managed, and the hydroclimate. Applying approximately 20 years of satellite records, we demonstrate a method to quantify the sensitivity and stability of land-atmosphere interactions. Here we evaluate the predictability of vegetation via the Normalized Difference Vegetation Index (NDVI) across croplands, shrublands, grasslands, and woodlands of East Africa as it relates to fluctuations in precipitation, soil moisture, evapotranspiration, and land surfaced temperature. In this study, we detect the strength of state dependency among these variables at the dekadal (10-day) to monthly scale using a data-driven approach known as Empirical Dynamic Modeling (EDM). There is notable spatial variability in NDVI predictability, with equatorial areas generally expressing the poorest skill, which can be attributed to the inconsistent rainfall seasonality and high aridity. Woodlands exhibit strong predictability throughout the region while vegetation response to environmental drivers in grasslands is less reliable. Our results suggest water availability, uptake and storage are important factors influencing the NDVI cycle. For a one-month lead time, high predictive skill can be retrieved from the time series, though skill weakens by a four- to sixth-month lead, at which point the overall seasonality appears to play a dominant role. One contribution to highlight is the advancement in our understanding of the relationship between vegetation and land surface temperature, which is particularly valuable in drought-prone East Africa. In this presentation, we introduce an application of EDM for biogeosciences, assess how historical seasonal information of the hydroclimate and vegetation across various land use and land covers can inform future environmental patterns, and identify critical areas of inquiry with a changing climate and extending agricultural production.
Where the north wind meets the sea: rainfall variability and change and its implications for food security in the Sahel
Authors: Gaasbeek Timmo , van der Ent Ruud , Coumou Dim , Haarsma Rein , Keulers Sander
Published: February 2023

Many factors have been suggested to explain variability and change in Sahel rainfall. Of those, sea surface temperature (SST) in the Eastern Mediterranean Sea (EMS) and zonal moisture flux south of the Sahel show strong correlations. Based on observational and reanalysis data on temperature, pressure, wind and moisture flux, this paper identifies a mechanism that explains both correlations. The mechanism hinges on the Jebel Marra massif and the Ethiopian highlands, where the mesoscale convective systems (MCSs) develop that bring most of the rain to the Sahel. We find that cold SST anomalies in the EMS between June and September cause a greater trans-Sahara temperature contrast and coincide with high pressure over Libya, resulting in stronger northerlies towards Sudan. This prevents Tropical Atlantic moisture from reaching the MCS genesis region, which reduces the seasonal northward spread of Sahel rainfall and of the Atlantic intertropical convergence zone, which in turn suppresses the development of the west-African westerly jet and the African westerly jet and inhibits Atlantic moisture from reaching the MCS genesis region, thus further reducing Sahel rainfall. Anomalous moisture transport from the Mediterranean does not play a role. Mediterranean SST variability raises questions about the future development of Sahel rainfall. If a new dry period materialises, this will have substantial implications on food production in the region. There are however opportunities for mitigating against the effects of such a dry period.
Three-dimensional numerical simulation of multiphase filtration and fracture propagation at the pore scale
Authors: Taurenis Denis , Nachev Victor
Published: February 2023

Over the past years in the development of oil and gas fields, there has been a trend towards an increase in the development of unconventional low-permeability reservoirs. In this regard, it is becoming increasingly important to study the problems associated with the use of hydraulic fracturing technology (HF) in rocks with a complex internal structure. To achieve the maximum oil and gas production rate and increase the drainage zone in the near-wellbore space, it is necessary to carry out hydraulic fracturing with the most extensive system of fractures.In this work the authors investigate the propagation of a hydraulically driven fracture in a fully saturated, permeable, and porous medium at the pore scale. To achieve a goal, at the first stage, we set a system of determining ratios and a crack propagation criterion. At the next stage, a three-dimensional numerical poroelastic model of a rock sample is prepared based on a three-dimensional image of the pore space of rock samples. Then numerical poroelastic modeling of the processes of one- and two-phase filtration and rock destruction using the extended finite element method is performed. For a more accurate description of filtration processes, the authors have prepared a physico-mathematical model that takes into account the flow rate and leakage of fluid into the rock during fracture growth at the pore scale. The obtained numerical results are compared with the previously conducted results of laboratory studies.As a result of the numerical simulation, the authors prepared a digital rock model (DRM) based on microCT data, performed numerical simulation of the filtration process in the DRM and numerical simulation of fracture propagation in a fully saturated, permeable, and porous medium at the pore scale. Then, the dependences of filtration, initiation and fracture propagation were investigated depending on various conditions of HF fluid injection.
The fast component of the solar wind: origins, correlations and modeling with EUHFORIA
Authors: Samara Evangelia , Magdalenic Jasmina , Rodriguez Luciano , Poedts Stefaan , Georgoulis Manolis K. , Pinto Rui F. , Arge Charles N. , Heinemann Stephan G. , Hofmeister Stefan J.
Published: February 2023

It is widely known that the fast solar wind originates mainly from coronal holes (CHs) in the solar corona. Associations between the CH characteristics and the properties of the fast solar wind in situ have been studied throughout the years from different authors leading to diverse degrees of correlation (Nolte et al. 1976; Vršnak et al. 2007; Karachik et al. 2011; Rotter et al. 2012a; Hofmeister et al. 2018; Heinemann et al. 2020). In this work, we introduce and quantify the geometrical complexity of CHs, a parameter that has been neglected so far in similar studies. For a particular CH sample, we explore how complexity affects the peak speed of the fast solar wind at Earth and its association with other CH properties. We further compare observations of fast solar wind at Earth with forecasts from EUHFORIA. We evaluate our results, and present the efforts and restrictions we encounter towards improving our prediction capabilities by exploiting recent PSP observations. 
Uivak II augen gneiss from the Saglek Block, Labrador: the current state of play
Authors: Keluskar Tanmay , Kusiak Monika A. , Dunkley Daniel J. , Whitehouse Martin J. , Wilde Simon A. , Yi Keewook , Lee Shinae
Published: February 2023

Interpreting Archean geology is often challenging due to the rocks having obscure field relationships and polymetamorphic histories (Kusiak et al. 2019; Dunkley et al. 2020). In such circumstances, U-Pb isotopic analysis of zircon is crucial for revealing the geological history. This study investigates Archean gneisses from the Saglek Block in Canada, which record magmatic and metamorphic history between ca 3.9 Ga and 2.5 Ga. The predominant lithology is the Uivak gneiss which is primarily composed of tonalite-trondhjemite-granodiorite (TTG) with subordinate intermediate to mafic components. Uivak gneiss is traditionally divided into Uivak I and Uivak II, where Uivak I is grey gneiss and Uivak II is characterized by augen texture and Fe-rich geochemistry (Collerson and Bridgwater, 1979). Ages for the magmatic protoliths of Uivak I are >3.6 Ga, whereas Uivak II ages vary between ca 3.6-3.3 Ga (Sałacińska et al. 2019; Wasilewski et al. 2021 and references therein). This study presents geochemical and U-Pb zircon geochronology from Mentzel and Maidmonts Islands. Augen gneiss on Mentzel Island fits the definition of Uivak II augen gneiss and yield a U-Pb zircon age of ca 3.3 Ga. A similar age was reported for Maidmonts gneiss (Sałacińska et al. 2019) and Illuilik gneiss (Wasilewski et al. 2021). On Mentzel Island, granitic bodies intruded the augen gneiss at ca 2.7 Ga and 2.5 Ga during high-T metamorphism. New dating confirms that augen gneiss on Mentzel Island and elsewhere in the Saglek Block belongs to Uivak II gneisses of ca 3.3 Ga. Variations in rare earth element concentration between different ca 3.3 Ga rocks can be attributed to the involvement of different crustal components in the magmatic protolith. On Maidmonts Island, the augen gneiss intrudes grey gneiss with a protolith age of ca 3.7 Ga, which confirms deformation and metamorphism of Uivak I gneiss before ca 3.3 Ga. This research was funded by NCN grants UMO2019/34/H/ST10/00619 to MAK.                  References:Collerson, K.D. & Bridgwater, D. 1979. Metamorphic development of early Archaean tonalitic and trondhjemitic gneisses: Saglek area, Labrador. In: Barker, F. (Ed.), Trondhjemites, Dacites, and Related Rock. Elsevier, Amsterdam, 205–271.Dunkley et al. 2020. Journal of the Geological Society, 177 (1), 31–49.Kusiak et al. 2018. Chemical Geology, 484, 210–223.Sałacińska et al. 2019. International Journal of Earth Sciences, 108, 753-778.Wasilewski et al. 2021. Precambrian Research, 359, 106092.
Predictive hazards from convective systems with deep learning
Authors: Leinonen Jussi , Hamann Ulrich , Sideris Ioannis , Germann Urs
Published: February 2023

Convection is a complex spatiotemporal process, which has made it a particularly attractive application for deep learning, which excels at both spatial and temporal reasoning. We have developed deep learning models for predicting the occurrence of hazards caused by convective storms, so that this information may be used by forecasters, emergency services and infrastructure managers to respond to the threats caused by these hazards.Our network is based on a recurrent-convolutional architecture that can process input data at multiple resolutions. It issues probabilistic predictions of hazard occurrence, currently up to 1 hour to the future. As inputs, we use data from weather radars, geostationary satellites, ground-based lightning detections, numerical weather predictions and digital elevation models. We have studied the importance of each data source to the quality of the predictions, finding that radar-based inputs contribute most to the prediction quality; however, some hazards can be well predicted also without radar, indicating that it is plausible to create warning systems for these hazards in areas where radar networks are not available.In this presentation, we will describe the model architecture and case studies, as well as our experiences so far in bringing the model to real-time use by forecasters and automated warning systems at MeteoSwiss. We will also discuss future directions of this research.
Resolution-enhanced Hyperspectral EnMAP data: CubeSat-based high resolution data fusion approach
Authors: Angulo Victor , Johansen Kasper , Rodriguez Jorge , Lopez Omar , Elfarkh Jamal , McCabe Matthew
Published: February 2023

Hyperspectral (HS) images obtained from space are useful for monitoring different natural phenomena on regional to global scales. The Environmental Mapping and Analysis Program (EnMAP) is a satellite recently launched by Germany to monitor the environment and explore the capabilities of hyperspectral sensors in the 420 and 2450 nm range of the spectrum. However, the data captured by the EnMAP mission have a ground sampling distance (GSD) of 30 m. This limits the use of the data for some applications that require higher spatial resolution (<10 m). This study examines the potential for improving the resolution of hyperspectral data using high resolution multispectral (MS) data obtained by Cubesats. Specifically, this work uses the data captured by the PlanetScope constellation, which has more than 150 CubeSats in low Earth orbit, with a high spatial and temporal resolution. The approach adopted leverages (1) the spectral capability of the hyperspectral EnMAP sensor, with a bandwidth of 6.5 nm in the visible and near infrared (VNIR) range (420–1000 nm) and 10 nm in the SWIR range (900–2450 nm), and (2) the spatial capability of the multispectral PlanetScope data, with a GSD of 3 meters, to enable significant spatial improvements due to its high spatial resolution. The main components of this work include: (i) area of interest clipping (ii) data co-registration, (iii) HS-MS data fusion, and (iv) quality assessments using the Jointly Spectral and Spatial Quality Index (QNR). In this study, a 2 km x 2 km area of interest was selected in the Malaucene region of France, where six state-of-the-art HS-MS fusion methods were evaluated: (1) fast multi-band image fusion algorithm (FUSE), (2) coupled nonnegative matrix factorization (CNMF), (3) smoothing filtered-based intensity modulation (SFIMHS), (4) maximum a posteriori stochastic mixing model (MAPSMM), (5) Hyperspectral Superresolution (HySure), and (6) generalized laplacian pyramid hypersharpening (GLPHS). Quality assessments of the enhanced data showed that high spectral and spatial fidelity are maintained, with the best performing fusion method being FUSE with a QNR of 0.625 followed by the MAPSMM method with a QNR of 0.604. Overall, this study advocates the benefits associated with the fusion of hyperspectral and multispectral data to obtain enhanced EnMAP data at 3 m GSD. 
Coupling Models of Plate Motion History, Mantle Convection and the Geodynamo to explain long-term Geomagnetic Field Behavior
Authors: Dannberg Juliane , Thallner Daniele , Gassmoeller Rene , Sprain Courtney , LaCombe Frederick , Ritchie Chloe
Published: February 2023

Mantle convection and plate tectonics are crucial mechanisms for keeping conditions at the Earth’s surface in a suitable range for life. One important mantle process is the transport of heat out of the Earth’s outer core, which impacts the geodynamo that generates Earth’s magnetic field. This interaction makes it possible to use changes in the paleomagnetic record to infer the past dynamics of the Earth’s mantle and core.We here couple a plate reconstruction, 3d global mantle convection models, and geodynamo simulations to quantify the largest possible influence of mantle heat transport on the magnetic field at the Earth’s surface. To constrain the core-mantle boundary heat flux, we set up compressible global mantle convection models using the geodynamic modeling software ASPECT, with material properties computed based on a mineral physics database. We prescribe the velocities at the surface using a plate reconstruction that describes plate motion history throughout the last 1 billion years, encompassing the complete cycle of supercontinent assembly and dispersal. This boundary condition imposes the location of subducted slabs in the model, which then sink down and interact with the thermal/thermochemical boundary later at the base of the mantle, affecting the amplitude and pattern of the heat flux out of the core and how it changes over time. Our models show that the distribution of hot and cold regions changes in terms of location, shape and number throughout the supercontinent cycle, depending on subduction location. Our results indicate that structures at the core-mantle boundary fluctuate and might have looked very differently throughout Earth’s history.We then select endmember scenarios of core-mantle boundary heat flux patterns and amplitudes to apply them as boundary conditions to thermally driven numerical geodynamo simulations. To assess how well these simulations reproduce Earth’s long-term magnetic field behavior, we apply the Quality of Paleomagnetic Modeling criteria. This allows us to systematically explore the impact of the most extreme variations of CMB heat flux on the geodynamo and to determine if extreme anomalies in the paleomagnetic record, like the extreme weak field period in the Ediacaran, could be caused by mantle dynamics alone or if they require other mechanisms, such as the nucleation of the Earth’s inner core.Our work shows how integrating multidisciplinary datasets into modeling studies improves our understanding of the mantle’s role in regulating the magnetic field throughout Earth's history, allowing us to re-evaluate the causes of variations in paleomagnetic data.
Towards parallel-in-time algorithms for numerical weather prediction
Authors: Shipton Jemma , Cotter Colin , Wingate Beth
Published: February 2023

Parallel-in-time algorithms provide a route to increased parallelism for weather and climate models, addressing the issue of how to make efficient use of future supercomputers. In this talk I will present an overview of the approaches implemented in Gusto, the compatible finite element dynamical core toolkit build on top of the Firedrake finite element library. Compatible finite element methods are of interest for weather and climate modelling due to their conservation and wave propagation properties on non-orthogonal meshes such as the cubed-sphere. These non-orthogonal meshes allow for better scaling from spatial domain decomposition than meshes based on the latitude-longitude grid which have grid points clustered at the poles. However, the sequential nature of classical timestepping algorithms is a bottleneck to increased parallelisation. Numerical weather prediction is a challenging application for time-parallel schemes due to the hyperbolic nature of the partial differential equations that make up the dynamical core. Several different time-parallel schemes are under investigation in Gusto: parallel exponential integrators using a rational approximation (REXI); asymptotic parareal, which uses averaged equations to construct the coarse approximation; and schemes based on deferred correction. I will give an overview of these methods and present the latest results and challenges.
Effects of urban structures on spatial and temporal flood distribution
Authors: Shlewet Marlin , Caviedes-Voullième Daniel , Kästner Karl , Hinz Christoph
Published: February 2023

Urban pluvial flooding is a modern, growing global disaster, particularly in developing countries with inadequate infrastructure. It remains a challenge to accurately model the runoff behavior in urban areas with a complex topography and to quantify the impact of spatial urban patterns on changing urban rainfall-runoff response. The question to be addressed is how varying the urban spatial configurations can quantitatively influence the overland flow response in relation to the spatiotemporal hydrodynamic variables such as water depth, velocity, and outflow discharge. We use a 2D shallow water model to indicate the influence of changing spatial urban factors (such as the orientation of streets and buildings, and adding sidewalks) in small idealized (synthetic) urban catchments during a single pluvial flood event. The domain layout extends over a size of 267.5m*267.5m with a 3% longitude slope. We differentiate mainly between two street networks: i) the two-way main street with of 14-m width with sidewalks, and ii) side streets of 10m width (Fig.1). We then define novel spatially integrated indicators over the domain at the steady state to analyze quantitatively runoff variables in correlation with the urban features (Fig.1). Additionally, local hotspot maps were created to assess the flood-risk thresholds, such as human stability and failure of buildings. Hotspots are defined as the places with the highest flow velocity magnitudes and water depths (> 90%). The results of the modeling showed that, with respect to the flow velocities in small-scale urban catchments, the main street layout is the dominant urban factor, followed by the side street widths, which were decisively determined by the geometry of the sidewalks. The comparison with real flood risk thresholds shows that the lower part of the main road is the most sensitive to flood risk in the domain with a high-risk hazard for human stability. However, the riskiest case is not corresponding to the fastest hydrograph response. Varying the spatial urban configurations, especially the rotation of the main roads, changes the flood risk thresholds and delays runoff. On the other hand, spatially integrated indicators of the flow variables in the domain are showing low sensitivity to the spatial urban features. Our findings offer a new important perspective on the development of urban flood risk assessment, especially for rapidly urbanizing cities, and provide a better understanding of the spatiotemporal rainfall-runoff generation in a small urban catchment considering the spatial layout of the urban structures.Fig.1 Overview of the modelling approach and evaluation of the runoff data
TILDAS measurement of multiple clumped isotope ratios in carbonates: progress and new horizons
Authors: Nelson David , Herndon Scott , Wang Zhennan , Quade Jay , Dettman David
Published: February 2023

Isotopic analysis using high resolution Isotope Ratio Laser Spectroscopy (IRLS) has been shown to be advantageous to multiple geochemical applications during the last decade.  These advances include isotopic analysis of the bulk isotopic compositions of water, carbon dioxide, methane and nitrous oxide.  More recently, laser spectroscopy has been used by several groups to examine the isotopic compositions of methane, carbon dioxide and nitrous oxide when carrying two rare isotopes (so called clumped isotopes).   Our recent work using Tunable Infrared Laser Direct Absorption Spectroscopy (TILDAS) has demonstrated highly accurate (~0.01 ‰) measurements of the clumped (16O13C18O or 638 in HITRAN isotope notation) isotopic composition of carbon dioxide derived from carbonate samples with spectroscopic measurement times of ~30 minutes using a dual laser spectrometer.  That spectrometer is optimized for the measurement of the four isotopologues required to calculate Δ638 (or Δ47).  We present here our parallel project to develop a novel dual laser isotope analyzer capable of measuring multiple carbon dioxide isotopic signatures simultaneously.   Specifically, we simultaneously measure the isotopic abundances of the three most abundant clumped isotopologues (Δ638, Δ637 and Δ828) as well as 17O oxygen excess or Δ17O.  Δ638 and Δ828 correspond to the quantities Δ47 and Δ48 when measured by isotope ratio mass spectroscopy (IRMS).   Δ17O is very difficult to measure with IRMS and Δ637 has not been previously measured with any technique to the best of our knowledge.  The new instrument utilizes carefully chosen spectral windows, operates at low sample pressure and exploits automated laser frequency hopping.  This prototype instrument simultaneously measures seven isotopologues of carbon dioxide: 626, 636, 628, 627, 638, 637 and 828.  Our preliminary results for Δ828 (or Δ48) are displayed as an Allan-Werle plot which shows that the precision in the measurement of Δ828 is ~0.09‰ for a single 3 minute sample measurement referenced to a working reference gas.  The plot shows that instrumental drift is very small over periods of several hours and that the precision can be improved to 0.03‰ by processing 10 sub-samples or to 0.01‰ by processing 100 sub-samples.  These measurements are preliminary and somewhat idealized but show promise for this new technique.
Investigating links among heatwaves, precipitation, and land use types using the Convection-Permitting Model in the Southwest UK for the 2022 boreal summer
Authors: Chun Kwok Pan , Ezber Yasemin , Toker Emir , Simões Reboita Michelle , Porfirio da Rocha Rosmeri , Risanto Bayu Christoforus , Yetemen Omer , Octavianti Thanti , Quinn Nevil , Sens Omer Lutfi , Castro Christopher
Published: February 2023

To improve sub-seasonal forecasts, different global initiatives generate continental convection-permitting simulations for resolution less than 10 kilometres for multiple decades. These simulations, however, are based on land use maps with only single urban type. In this study, we explore how the density and height information of the urban canopy based on Local Climate Zones (LCZs) affect the dynamics among temperatures, precipitation and land use types for the 2022 summer heatwave in the Southwest UK. Four numerical experiments at a 3 km grid are run by switching off the parameterization of deep-convection in the Weather Research and Forecasting (WRF) models. These experiments are based on (i) the no urban scenario, (ii) the default MODIS land use scheme, (iii) the building environment parameterization (BEP), and (iv) the building energy model (BEM).Results show that the cold advection over the UK led to downward motion according to a Q-vector analysis. The regional downward motion caused the formation of a heat dome. It is against the hypothesis that the 2022 summer heatwave was due to the hot circulation from Spain and equatorial Africa. Even though four land use schemes have similar simulated cold advection across the UK, our findings show that land use types affected water recycling due to local convection differently. These differences were related to the strength of rainstorms at the dissipating heatwave stage. Our results suggest that urban areas were more likely to have more persistent heatwaves since the intensity of rainstorms was affected by the lower local water recycling. This advanced understanding of the UK heatwave mechanism based on regional advection conditions and local convection processes will guide us on how to improve our sub-seasonal forecast in the urban area.
Fragmentation of the Victoria microplate: geomorphological evidence for active faulting along the Isuria-Utimbara fault system, Kenya-Tanzania transboundary region
Authors: Kahle Beth , Ludat Alina , Kübler Simon , Zebari Mjahid , Rieger Stefanie , Dusingizimana Mugabo Wilson , Carena Sara , Friedrich Anke
Published: February 2023

The Victoria microplate is generally assumed to be internally rigid, i.e. non-deforming.  Here, we describe geomorphological evidence for active fragmentation of the microplate along the E-W to NE-SW striking Isuria-Utimbara fault system, Lake Victoria, in the Kenya-Tanzania transboundary region.The Isuria-Utimbara fault system has received little previous attention and is not recognised as seismically active. The fault system marks the northern boundary of the Mara River Basin and lies within the mapped extent of the Victoria microplate, an apparently relatively rigid block situated on the Tanzanian craton. The area is defined by low seismicity within the temporal limits of the instrumental record: seismicity is concentrated along the western arm (as well as, to a lesser extent, the southernmost part of the eastern arm) of the East African Rift (EAR). Here, we describe geomorphological evidence for geologically recent earthquake activity, which has produced scarps and alluvial fans in the hanging walls of the major escarpments. The scarps appear to be segmented, with typical segment lengths of approximately 15 km, and together sum to an along-strike length of approximately 100 km. The height of the scarps exceeds 8 m with a maximum height of 25 m (measured using TanDEM-X Digital Elevation Model (DEM) Global data which has a horizontal resolution of 12 m and an ~2 m height error). Considering the length of a typical segment, scaling relationships suggest the possibility for multiple >Mw 6 earthquakes. If the segments slipped together, this would result in a maximum earthquake magnitude of >7. Although dating has not yet been carried out, a constraint on slip rate comes from displaced Neogene volcanics found above and below the main escarpment, which give a long-term vertical displacement rate of approximately 0.1mm/yr, comparable with stable continental intraplate settings. Our findings have implications for the seismic hazard of the region: although parts of the Mara River Basin are protected areas of great ecological importance, population density is increasing along the shores of Lake Victoria and a major gold mine lies directly to the south of the fault system. This fault appears to be fragmenting the Tanzanian craton, albeit at relatively slow rates, and cratonic settings are in general capable of producing large and damaging earthquakes due to the possibility for a large seismogenic thickness.
Seismic response to volcanic processes at Mount Etna: coupling thermomechanical simulations with seismic wave-equation modeling
Authors: Bensing Michelle , Vinciguerra Sergio , De Siena Luca
Published: February 2023

Mt. Etna, located in the north-eastern area of Sicily (Italy), is one of the most active and hazardous strato-volcano in the world, both in terms of paroxysmal events and continuous effusive activity from the summit area and hazardous flank eruptions. Long-term processes of deep magma recharge and storage within the upper crust, passive magma ascent along pre-existing weaknesses, and forceful dyke intrusions allow magma to rise to the surface. Past studies provided evidence supporting the view that the interplay between magma dynamics and storage and the thermomechanical response of the host medium control magma rise and the brittle seismic response of the volcano basement and edifice. To further investigate this interplay, we have performed 3D thermomechanical simulations of the present-day state of the volcano using the Lithosphere and Mantle Evolution Model (LaMEM) code. The model is built between the volcanic surface and 30km depth and includes realistic topography. Magma storage zones within the model are inferred from seismic tomography and seismic source studies at ~30km (deep storage) and between 3 and 6 km (shallow storage). The characteristics of the molten zones are calibrated by physical and mechanical properties determined for the main representative lithologies (carbonates, basalts, clays) and the corresponding rheological laws. As we are interested in the present-day dynamics of the volcano, we ran our models for just a few timesteps to gain surface velocity and displacement data.The LaMEM framework allows retrieving both deformation and gravity responses to the final model. These responses will be fit to real GPS, InSAR, and gravity data to define the most realistic properties of the Etna feeding systems. Future steps will include tectonic forces contributing to the sliding of the eastern volcanic flank in the simulation and propagation of seismic waves in the final model suitable to fit existing seismic data.
Estimating and Simulating Precipitation Uncertainty Data for Large-Scale Hydrologic Applications
Authors: Wright Daniel , Hartke Samantha , Li Zhe , Peng Kaidi , Alexander Aaron , Liu Yuan
Published: February 2023

The usefulness of satellite multi-sensor precipitation and other large-scale precipitation products in hydrologic applications can be hindered by substantial uncertainty. In parts of the world with few ground observations of precipitation, such uncertainty is difficult to quantify. At the same time, how to cope with the characterize and model the spatiotemporal structure of this uncertainty has been called a grand challenge within the precipitation community. We present progress on two fronts which, when combined, addresses this grand challenge. Rather than relying on ground reference data to quantify uncertainty in NASA’s IMERG precipitation dataset, we instead use the dual-frequency precipitation radar aboard the NASA/JAXA GPM platform. This uncertainty information is then fed into the Space-Time Rainfall Error and Autocorrelation Model (STREAM), which uses an uncalibrated anisotropic and nonstationary spatiotemporal correlation modeling approach to stochastically generate ensemble precipitation fields that depict the uncertainty inherent in IMERG. We then use these ensemble fields to examine the effects of precipitation uncertainty in several hydrologic applications, including flood monitoring and prediction of water and energy fluxes. Ensemble-based hydrologic simulations outperform those based on IMERG and help reveal the spatiotemporal scales and hydrologic variables for which precipitation uncertainty is critical. The approach is compatible with other continental-to-global scale precipitation estimates such as those from numerical weather models, and can also be used in precipitation downscaling contexts. We are developing a set of open-source tools to facilitate its usage.