bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial and temporal evolution of Skaftá cauldrons floods from 2015 to 2021 through the analysis of correlograms
Authors: Nowé Sylvain , Lecocq Thomas , Caudron Corentin , Jónsdóttir Kristín , Einarsson Bergur , Vanderhoof Bethany , Pattyn Frank
Published: March 2022

In September 2021, two jökulhlaups were released into the Skaftá river from western Vatnajökull icecap (Iceland). Such floods have been known since 1955. These jökulhlaups originate from two subglacial lakes under 1–3 km wide and 50–150 m deep depressions in the glacier surface, commonly referred to as ice cauldrons, formed by geothermal melting. The average time interval between jökulhlaups from each cauldron is ~2 a. The jökulhlaups travel ~40 km under a glacier that reaches maximum thickness of ~750 m and emerge in the Skaftá river at the terminus of Skaftárjökull outlet glacier. In addition to increased subglacial water flow and river discharge, these floods are responsible for seismicity and tremor onset, inside the cauldrons, along the subglacial channels, at the outlet where the subglacial channels meet the river, as well as on the river path.
We used seismic interferometry or cross-correlation of seismic noise to analyse data from 2015 to the end of 2021. We computed cross-correlation functions for 27 seismic stations and for frequencies between 0.5 and 8 Hz. To characterize these floods, we calculated the propagation velocities based on the cross-correlation functions and for each frequency band. We located seismic signatures both during the floods period and previous times by using a grid-search method based on the approach of Ballmer et al. 2013, which calculates theoretical differential times and provides probabilities of locations as the summed stack amplitudes of correlograms. These daily location grids allowed us to analyse the spatial evolution of probability of location during these floods as well as compare them with previous “non-flood” periods. Furthermore, based on these location grids, we were able to compute temporal series for isolated locations (pixels) such as ice cauldrons, a hydrological station located on the river path, or any other target, allowing us to analyse the temporal evolution of location probability during the floods as well as compare it with the last six years of data. The resolution of this temporal evolution ranges from monthly to hourly. By using six years of seismic data, we were also able to compare the 2021 floods with floods due to the same ice cauldrons, for example in August 2018 and September 2019.
This study provides an insight on how relevant seismic interferometry can be in the monitoring of such processes, with the purpose of being fully automatic in the near future.
Palaeobiogeographic evolution and climatic adaptation within the plant family Linaceae
Authors: Bansal Mahi , Nagaraju Shivaprakash , Murthy Srikanta , Farooqui Anjum , Prasad Vandana
Published: March 2022

Around 37% of the Mediterranean territory is covered with polyploid angiosperms, of which the genus Linum occupies a considerable region. Linum is the most diversified genus of the plant family Linaceae that comprises a “family pair” of Hugonioideae distributed in tropical regions and Linoideae mainly distributed in temperate to subtropical regions. We provide the oldest fossils of Linaceae, comparable to the living genera Linum and Reinwardtia, from the Late Cretaceous Infratrappean Deccan volcano sedimentary sequences of Maharashtra, India. The phylogenetic analysis conducted by combining the morphological characters of the pollen fossils recovered and the pollen morphological as well as molecular characters of extant species of Linaceae reveals that the family originated in the wet and warm tropical zones of South America in the Late Cretaceous. Thereafter, the family dispersed to Africa giving rise to the lineage of Linoideae that further diverged into two main clades, one of which evolved either on seasonally wet areas of Kohistan-Ladakh Island arc (KLIA) or on the Indian Plate in Maastrichtian-Paleocene. The second clade encompassing the genus Linum originated on seasonally wet areas of Africa and later dispersed to Mediterranean region via Boreotropical route in Paleocene where it adapted to seasonally dry climatic conditions that prevailed during late Eocene. The family further expanded its geographical range and spread to Eurasia, and to North America via Bering land bridge. We also propose the dual colonization of Linaceae in India. The seasonally wet lineages dispersed from Africa to India via KLIA in the Maastrichtian-Paleocene. Whereas, the seasonally dry lineages of Linum migrated from Eurasia into India probably during the Oligocene when the climatic conditions were dry and warm arid. The decline in global temperature towards the end of Eocene escalated the diversification rates within Linaceae that is currently found in the regions of meso- and microthermal climate. The next major shift in diversification rate was detected on the crown node of North American Linaceae during the Middle Miocene Climate Transition.
Machine learning tools for pattern recognition in polar climate science
Authors: Gregory William
Published: March 2022

Over the past four decades, the inexorable growth in technology and subsequently the availability of Earth-observation and model data has been unprecedented. Hidden within these data are the fingerprints of the physical processes that govern climate variability over a wide range of spatial and temporal scales, and it is the task of the climate scientist to separate these patterns from noise. Given the wealth of data now at our disposal, machine learning methods are becoming the tools of choice in climate science for a variety of applications ranging from data assimilation, to sea ice feature detection from space. This talk summarises recent developments in the application of machine learning methods to the study of polar climate, with particular focus on Arctic sea ice. Supervised learning techniques including Gaussian process regression, and unsupervised learning techniques including cluster analysis and complex networks, are applied to various problems facing the polar climate community at present, where each application can be considered an individual component of the larger sea ice prediction problem. These applications include: seasonal sea ice forecasting, improving spatio-temporal data coverage in the presence of sparse satellite observations, and illuminating the spatio-temporal connectivity between climatological processes.
Seasonal and regional analysis of Arctic sea-ice evolution
Authors: Ritschel Markus , Notz Dirk
Published: March 2022

We examine the seasonal and regional evolution of sea-ice coverage in the Arctic. Using satellite and reanalysis data in comparison with model simulations of the 6th model intercomparison project (CMIP6), we build on studies (e.g. Niederdrenk and Notz, 2018; SIMIP Community, 2020) that have found a strong linear relationship between September sea-ice area of the northern hemisphere and global atmospheric air temperature (TAS) as well as anthropogenic CO2 emissions. Instead of focusing on the whole Arctic and September sea ice, we perform sensitivity analyses on higher-resolved regional and seasonal scales, aiming to identify the atmospheric and oceanic drivers that govern the evolution of sea-ice coverage on these scales and to derive simple empirical relationships that describe the impact of these processes. We find clear linkages also on these higher-resolved scales, with different regions and different seasons showing diverse sensitivities of sea-ice area evolution with respect to TAS and anthropogenic CO2. Furthermore, we make use of the Mahalanobis distance as a multivariate metric to quantify the "quality" of a single simulation matching the observations, thereby considering the different sensitivities of all months of the year. Building the combined covariance matrix of the observations and simulations as a measure of the joint uncertainties, we can determine how "close" to the observations each single member of the simulations is. This allows us to separate models whose sensitivities are in overall good agreement with the observations from those that are apparently not capable of properly simulating the response of the sea ice to the forcing throughout all months.
Based on our findings we can infer the dominant drivers that force Arctic sea-ice evolution on a regional and seasonal scale and also derive projections for the future evolution of Arctic sea ice for different climate scenarios based on simple empirical relationships that can directly be estimated from observational records.

References:
Niederdrenk, A. L., & Notz, D. (2018). Arctic sea ice in a 1.5 °C warmer world. Geophysical Research Letters, 45, 1963–1971. https://doi.org/10.1002/2017GL076159
SIMIP Community (2020). Arctic sea ice in CMIP6. Geophysical Research Letters, 47, e2019GL086749. https://doi.org/10.1029/2019GL086749
Flash droughts early warning based on evaporative stress forecasts
Authors: Gou Qiqi , koppa Akash , E. Beck Hylke , Hulsman Petra , G. Miralles Diego
Published: March 2022

Flash droughts are regional phenomena that can manifest in region areas with a rapid intensification, and that often last for short periods of time. Flash droughts have received considerable scientific attention in recent years. However, their prediction is still a challenge, largely due to their abrupt onset and often unknown regional drivers. Here, we establish a forecast system to predict flash droughts at a medium-range weather scale. The system uses forcing data from the Multi-Source Weather (MSWX), an operational, high-resolution (3‑hourly, 0.1°), bias-corrected meteorological product with global coverage from 1979 to several months into the future (Beck et al. 2021). MSWX data are used as input to the Global Land Evaporation Amsterdam Model (GLEAM), more specifically its recent hybrid version (Koppa et al., 2021). This allows us to compute forecasts of actual and potential evaporation;  the ratio of both (also know as 'evaporative stress') is used here as flash drought diagnostic. This forecast system is evaluated on its ability to predict flash droughts globally and 2, 4, 7 and 10 days advance. The new tool shows potential to improve our understanding of flash droughts, and it serves as an early prediction system to enable more efficient agricultural and water management.

 

References:

Beck, H. E., Wood, E. F., Pan, M., Fisher, C. K., Miralles, D. M., van Dijk, A. I. J. M., McVicar, T. R., and Adler, R. F., MSWEP V2 global 3‑hourly 0.1° precipitation: methodology and quantitative assessment. Bulletin of the American Meteorological Society. 100(3), 473–500, 2019

Koppa, A., Rains, D., Hulsman, P., and Miralles, D. M., A Deep Learning-Based Hybrid Model of Global Terrestrial Evaporation. Preprint. 2021. 10.21203/rs.3.rs-827869
S-to-P Receiver Function Analysis of The New Zealand Subduction Zone
Authors: Buffett William , Harmon Nicholas , Rychert Catherine , McNeill Lisa
Published: March 2022

Subduction zone dynamics are important for a better understanding of a broad range of topics ranging from plate tectonics to natural hazards such as earthquakes and volcanoes. New Zealand is a seismically unique place, resting on the Hikurangi Subduction Zone. It experiences a large range of seismic phenomena from evidence of large megathrust events and slow slip activity, to active volcanism within the Taupo Volcanic Zone. Although much seismic imaging has been performed, S-to-P receiver functions can tightly constrain discontinuities and associated dynamics. Here we use S-to-P receiver functions to image lithospheric discontinuities beneath the North Island of New Zealand using IRIS-DMC and Geonet stations. We image the Moho at 15-25 km depth in the south by Wellington, with a second velocity increase with depth imaged just beneath at 40-50 km, possibly corresponding to the Moho of the downgoing plate. On the northern edge of the North Island by Auckland, the Moho is imaged at 20 +/- 5 km depth. Near Napier and Lake Taupo we image 2 positive discontinuities at 10 and 30 km depth, still beneath the upper plate potentially related to crustal layering or the magmatic plumbing system. This is in line with previous studies of the Moho, for example a collation of Moho estimates by Salmon et al. (2013) places the Moho in the region of 20-25 km depth for most of the North Island, except for some deeper phases in the very east and the most southwest. A negative phase corresponding to the lithosphere-asthenosphere boundary (LAB) of the upper plate is imaged at 60-70 km depth across portions of the North Island. The LAB of subducting Pacific Plate is imaged at 70-80 km with the exception of a gap in the LAB phase between 39° and 40° latitude and around 176° longitude corresponding to the mountain ranges of Kaweka Forest Park and Ruahīne Forest Park. We image a velocity increase directly beneath the LAB, potentially related to the base of a melt layer beneath the plate. Furthermore, this is consistent with the estimated thickness of the lithosphere (73 +/- 1 km), for instance from the active source estimates of Stern et al. (2015).
Dependencies of morphology and lithological variations on tectonics, thermal structure and ocean loading at ultra-slow and slow ridges.
Authors: Mezri Leila , Gracià-Pintado Javier , Pérez-Gussinyé Marta , Liu Zhonglan , Wolfgang Bach
Published: March 2022

Why do some mid-ocean ridges have morphology that expresses oceanic core complexes with large gabbro bodies, while others have smooth seafloors with large exposures of serpentinized mantle or rough seafloors, while lavas are observed almost everywhere?

Over the past few decades, numerical models have inferred that the fundamental mechanism controlling the wide diversity of lithology, crustal thickness, and ridge morphology is the balance between magmatism and tectonics. Key controls on this modeled equilibrium are the melt supply rate, which varies to account for the discontinuous volcanism observed on slow ridges, and the thermal structure, which depends on the balance between heat injected during magmatic accretion and heat removed by hydrothermal cooling, modulated by the spreading rate.

Based on this paradigm, it has been established that the fraction of melt that is accreted into the crust controls the formation of large oceanic core-complexes and flip-flop detachments, with the former being formed at fractions corresponding of half of spreading rate and the latter being formed when the melt supply is much smaller.

However, several fundamental questions remain poorly understood or unanswered. Why can slip on oceanic detachment faults continue and why does it stop? How do serpentinization and magmatic intrusions play a role in crustal growth and how do they interact? How and why do mechanisms related to magma supply switch from magmatic to detachment dominated mode during oceanic accretion?

Here we present self-consistent numerical simulations of the development of mid-ocean ridges, starting  from continental rifting and breakup. In our models melt supply varies dynamically with extension velocity and is affected by faulting. We focus on understanding how tectonism, melting, serpentinisation and hydrothermal cooling interact to form smooth-seafloor, core complexes and normal igneous seafloor, and their diverse crustal lithology.
Long-distance sand transport to the temperate basalt plains of southeastern Australia: implications for atmospheric circulation just prior to the last glacial maximum
Authors: Fitzsimmons Kathryn , Gromov Sergey , Porch Nicholas
Published: March 2022

The Western Victorian Volcanic Plains of southeastern Australia is the third largest basalt province in the world. Whilst the climate of this region is presently temperate, it lies east and south of extensive dunefields which were active during more arid phases in the past.

While investigating the timing of fossil deposition at the Spring Creek megafaunal site – a locality initially argued to provide evidence for last glacial survival of extinct invertebrate taxa – we discovered a surprising quantity of sand-sized quartz within the clayey sediments of the deposit. Since quartz sand is not common in the Western Victorian basalt province or within underlying Tertiary marls, we propose this sand to be allochthonous and transported some distance. The quartz sand yields a particularly bright luminescence signal characteristic (although not diagnostic) of aeolian quartz from dune sediments to the west, and dates using single-grain optically stimulated luminescence to just prior to the Last Glacial Maximum.

In this study we investigate the potential for long-distance sand transport to the Spring Creek site on the Western Victorian basalt plains, by means of climate reanalysis and wind regime modelling for the LGM compared with the present-day time slices. We find that LGM wind regimes were dominated by strong, unidirectional westerly air flow at Spring Creek, compared with more variable and weaker wind orientations and velocities in the present day. Our results suggest stronger potential for eastward distal sand transport from the dunefields west of the basalt plains during the LGM. This enhanced wind strength and transport was coeval with enhanced aeolian activity in those dunefields, and with reactivation of sandy palaeoshorelines just to the south of them. Additional modelling of LGM wind vectors compared with aeolian accumulation onto securely dated transverse shoreline dunes of the same age in the Willandra Lakes to the north supports our findings, by indicating an intensification of westerly winds over the southeastern part of the Australian continent just prior to the LGM.
High-resolution satellite-based cloud detection for the analysis of land surface effects on boundary layer clouds
Authors: Fuchs Julia , Andersen Hendrik , Cermak Jan , Paui Eva , Roebeling Rob
Published: March 2022

This study aims at improving an empirical cloud masking approach for the high-resolution analysis of land surface effects on boundary layer clouds.

The observation of boundary layer clouds with high-resolution satellite data can provide comprehensive insights into spatiotemporal patterns of land surface-driven modification of cloud occurrence, such as the diurnal variation of the occurrence of fog holes and cloud enhancements attributed to the impact of the urban heat island. High-resolution satellite-based cloud masking approaches are often based on locally-optimized thresholds that are compared against satellite-observed reflectances to separate cloudy from clear-sky observations that can be affected by the local surface reflectance. Therefore, spatial differences in surface albedo, as found in and around urban areas or forests, can introduce spatial biases in the detected cloud cover that may impede the analysis of spatial pattern changes due to land surface influences. In this study, two approaches for cloud masking using the High Resolution Visible channel of the Spinning Enhanced Visible and Infrared Imager aboard Meteosat Second Generation are developed and validated for the region of Paris to show and improve applicability for analyses of urban effects on clouds. Firstly, a local approach that uses an optimized threshold to separate the distribution of visible reflectances into cloudy and clear sky for each individual pixel accounting for its locally specific brightness. Secondly, a regional approach that uses visible reflectance thresholds that are independent of surface reflection at the observed location. While the first approach is representative for the widespread usage of locally-optimized approaches, derived cloud masks result in regional biases that are caused by the differences in surface reflectance. This makes the regional approach a more appropriate choice for the high-resolution satellite-based analysis of cloud cover changes over different surface types and the interpretation of locally induced cloud processes.
Modelling the impact of spatial variability of precipitation on flood hazards in the Kathmandu Valley, Nepal
Authors: Creed Maggie , Muthusamy Manoranjan
Published: March 2022

In recent years, scientists have shown that the increasing trend in precipitation and flash floods during the monsoon season, combined with rapid land-use change, is leading to an increase in river discharge and flood inundation in the Kathmandu valley. The Kathmandu valley is a mid to low elevation mountain region (mean ~ 1250 m), surrounded by hills, particularly to the north, south and west, and has a population of over 3 million.  In this study, statistical analysis of 30 to 50 years of historical rainfall and river discharge data indicate a strong spatial variability in daily rainfall over the catchment during the monsoon season. Hilly regions which surround the Kathmandu basin receive significantly more rainfall than the valley, and rainfall intensity can vary greatly between the northern and southern hills, in particular. Combining our statistical analysis with physical-based numerical modelling of a range of historical flood events we demonstrate that the spatial variability in rainfall can lead to large differences in flood inundation patterns across the valley. Traditional flood early warning systems in the Kathmandu valley do not consider the effect of spatial variability of rainfall on flooding in the basin, which can lead to over or under predictions of flood extent in certain regions for a given event. We demonstrate that flood extent is the centre of Kathmandu and to the west of the city will be significantly higher if heavy rainfall occurs in the northern region of the valley.
Studying multi-beam ion temperature inside a collisionless reconnection plasmoid by means of Gaussian Mixture Model
Authors: Paramonik Igor , Divin Andrey , Zaitsev Ivan , Semenov Vladimir
Published: March 2022

Being ubiquitous energy converter is space plasmas, magnetic reconnection releases stored magnetic energy into kinetic energy of particles. Magnetic reconnection involves several particle acceleration mechanisms which form beams directed parallel to the magnetic field. It was recently demonstrated analytically that in the presence of complicated velocity space structures, the definition of higher moments (like thermal pressure) should be extended to cover such multibeam distributions. In practice, the number of beams at each spatial point of interest is not know a priori. With the aim to automatically reveal the information about the beams generated in the reconnection process, we applied an unsupervised machine learning algorithm (Gaussian Mixture Model, GMM) to the 2.5D Particle-in-Cell simulations of collisionless magnetic reconnection. We studied the ion distributions inside a plasmoid and found that the multibeam ion temperature  within the reconnected outflow deviates significantly from the standard ion temperature (calculated as the 2nd moment of the ion distribution function). In particular, the regions of the strong parallel heating contain in fact relatively cold counterstreaming beams and the overestimation of parallel temperature in this case could be as high as 10. In the current study, we make an attempt to figure out how long the multi-beam regime exists without significant thermalization inside a plasmoid formed by two adjacent X-lines.
Modelling the impact of cloud condensation and ice nuclei on the near-surface climate of Dronning Maud Land (East Antarctic) using the regional climate model COSMO-CLM²
Authors: Sauerland Florian , Van Lipzig Nicole , Souverijns Niels , Mangold Alexander , Van Overmeiren Preben , Wex Heike
Published: March 2022

By serving as condensation and ice nuclei, aerosols play a vital role in the formation of clouds. This has significant implications for the radiation balance and precipitation amounts over the Antarctic Ice Sheet, where type and amount of aerosols differ significantly from other places because of its remote location. However, that is also the reason observations are sparse, and consequently, few studies exist examining this effect. Recently, a module was added to the COSMO-CLM² regional climate model to account for the aerosol-cycle. The model was integrated for the region around the Princess Elisabeth Antarctic research station (PEA) in Dronning Maud Land for a period of 10 days in January 2016, of which the first 3 days were discarded. Varying cloud condensation and ice nuclei were prescribed to the model, based on observations from PEA. The model output was compared to observations of cloud structure and precipitation amounts taken at PEA, as well as the unmodified COSMO-CLM² model. The model integrations indicate that the number of ice nuclei has a significant impact on the microphysical composition of clouds, with higher numbers being associated with a lower amount of liquid water content of clouds and higher precipitation amounts. Additional runs are performed to confirm and extend these findings for an entire year. Recent measurements of ice nuclei particle concentrations obtained during two austral summers are also considered. Moreover, we analysed how atmospheric dynamics affect the cloud-aerosol interaction by analysing the model sensitivity for different weather regimes. 
Towards a green water planetary boundary
Authors: Wang-Erlandsson Lan , Tobian Arne , van der Ent Ruud , Fetzer Ingo , te Wierik Sofie , Porkka Miina , Staal Arie , Jaramillo Fernando , Dahlmann Heindriken , Singh Chandrakant , Greve Peter , Gerten Dieter , Keys Patrick , Gleeson Tom , Cornell Sarah , Steffen Will , Bai Xuemei , Rockström Johan
Published: March 2022

Green water - i.e., land precipitation, evaporation and soil moisture - is fundamental for the functioning of the biosphere and the Earth System, but is increasingly perturbed by continental-to-planetary scale human pressures on land, water and climate systems. The planetary boundaries (PB) framework demarcates a global safe operating space for humanity, but does hitherto not explicitly account for green water. Here, we propose a green-water boundary within the existing PB framework, of which a control variable could be defined as "the percentage of ice-free land area on which root-zone soil moisture deviates from Holocene variability for any month of the year". We provide provisional estimates of baseline departures based on CMIP6 data, and review the literature on soil-moisture induced deterioration in Earth System functioning. The evidences taken together suggest that the green water PB is already transgressed, implying that human modifications of green water need to come to a halt and be reversed. Future research needs to advance our understanding of root-zone water dynamics, including associated large-scale and potentially non-linear interactions with ecohydrology, hydroclimate, biogeochemistry and societies.
Testing the performance of a near-real time flood mapping framework jointly assimilating water levels from river gauges and satellite flood maps
Authors: Annis Antonio , Nardi Fernando , Castelli Fabio
Published: March 2022

High resolution flood forecasting models integrated in Early Warning Systems (EWSs) can be supported by traditional (e.g., stage gauges) or innovative (e.g., Earth Observation – EO - data) sensors as inputs or observations for model calibration/validation or data assimilation. Stage gauges provide information only in specific points along the river network and could fail during extreme events. On the other hand, EO data could have strong limitations due by their spatial and temporal resolution, especially at medium-small scales. Therefore, multiple sources of distributed flood observations could represent a solution for managing uncertainties of flood models and lack of information left by each sensor.

In this work, a flood modelling approach is proposed for the joint assimilation of both water level observations and EO-derived flood extents. The assimilation approach implements a Ensemble Kalman Filter, whose forecasting model includes a parsimonious geomorphic rainfall-runoff algorithm (WFIUH) and a Quasi-2D hydraulic algorithm. To overcome stability issues related to the updating of the Quasi-2D hydraulic model, novel approaches are proposed to both assimilate multiple stage gauge observations and retrieve distributed observed water depths from satellite images. The flood modelling chain is tested both separately and jointly assimilating stage gauges and satellite derived flood extents on a flood event for the Tiber river basin in central Italy. Results reveal that the assimilation of observations from static sensors and satellite images led to an overall improvement of the simulation performances in terms of Nash-Sutcliffe efficiency Pearson correlation and Bias to the Open Loop simulation. Moreover, the joint assimilation of the abovementioned observations allowed to reduce the flood extent uncertainty as respect to the disjoint assimilation simulations for several hours after the satellite image acquisition.
Subsidence in Askja Caldera between 2015 to 2021
Authors: Sepúlveda Josefa , Hooper Andy , Ebmeier Susanna , Novoa Camila
Published: March 2022

Iceland is in a Mid Ocean Ridge, where the North American Plate is moving far away from Eurasian Plate at a relative rate of 18-19 mm/yr. The boundary between plates is marked by an active neovolcanism expressed by different volcanoes centres and fissures swarms. Askja volcano is located in the North Volcanic Zone of Iceland. It has an area of 45 km3 and hosts three calderas. Three main eruptions have been observed during different periods: i) 1874 to 1876, ii) 1921-1929, and iii) 1961. Monitoring data have shown a period of alternance between subsidence and uplift between 1966 to 1972. Thereafter, since at least 1983 the caldera has been subsiding at a rate of 5 cm/yr, but this rate has been decaying slowing with time. Additionally, tomography data has revealed a possible deeper zone (between 9 and 15 km depth) below the volcano where melting is storage and also the seismicity between 20 and 25 km depth may be interpreted like a magma movement in this area. However, there are still questions about what is producing the subsidence at Askja. In this work, we present Interferometry Synthetic Aperture Radar (InSAR) results during the period of 2015 to 2021 in Askja. This data will help to constraint what is it causing the subsidence at Askja Caldera.
Exploration of high temperature aquifer thermal energy storage in Delft (The Netherlands)
Authors: Vardon Philip , Bloemendal Martin , Beernink Stijn , Hartog Niels , Barnhoorn Auke , Schmiedel Tobias , Abels Hemmo , Laumann Susanne
Published: March 2022

In conjunction with a deep geothermal project which is being implemented on the TU Delft campus in the Netherlands, a high temperature aquifer thermal energy storage (HT-ATES) is being considered. An initial feasibility study suggests that this could significantly reduce CO2 emissions from heating and be financially beneficial. As part of the research associated with the implementation of the geothermal well, a 500 m deep monitoring and exploration well has been drilled to further investigate two target layers for HT-ATES and to allow for scientific records before, during and after the production phase of the geothermal project. With this drilling, the potential for HT-ATES of multiple layers is investigated by means of innovative exploration methods. An extensive set of downhole geophysical logging tools was used, many cores from both consolidated and unconsolidated layers were taken and a pumping test was carried out in the deepest layer. This work presents an initial overview of the work carried out and provides insights into the initial results of this innovative exploration drilling. The Delft geothermal project is therefore a great example of a beneficial interplay of economic and societal interest (i.e. city heating, CO2-neutral campus) and scientific innovation.
Air temperature distribution and structure of katabatic wind on a shrinking mountain glacier
Authors: Nicholson Lindsey , Stiperski Ivana , Kehl Alexander
Published: March 2022

The glacier katabatic wind system represents a feedback mechanism (de)coupling the glacier and the overlying atmosphere, altering the glacier microclimate.

Still, there are only a limited number of distributed measurements of the atmospheric conditions above the glacier surface. In August 2018, eight weather stations, partly with turbulence measurements at two levels, were installed in the middle and lower part of the Hintereisferner valley glacier in Austria, yielding three weeks of data on the near-surface spatial pattern of atmospheric conditions. These data are used to (a) quantify the observed properties of the glacier wind with regard to its spatial variability, persistence, and the synoptic conditions that erode it and (b) assess how well methods to extrapolate near-surface air temperature over glacier surfaces are influenced by the existence of the glacier wind and match the available observations on Hintereisferner.

 

Despite data limitations and uncertainties, results show that the glacier wind persists under most synoptic conditions, and deepens and speeds up downglacier. However, significant disturbances such as cold front passages and rain events can cause erosion of katabatic wind for periods from minutes to days. Representations of near-surface temperature distribution over the glacier using classical lapse rates and the along flow-line modified Greuell-Böhm model showed variable agreement to the measured data, with evidence for dependency on ambient atmospheric conditions. However, interpretations of the performance of temperature extrapolations should be viewed with caution due to the absence of observations in the upper glacier. We consider how these findings can be included in surface energy balance models of future glacier evolution, and conceptually how this aspect of the glacier microclimate, and the wider valley circulation, can be expected to evolve with continued glacier shrinkage.
Cloud Microphysics Measurements and the Development of Precipitation During EUREC4A
Authors: Lloyd Gary , Choularton Thomas , Blyth Alan , Gallagher Martin , bower keith , Cui Zhiquang , Denby Leif
Published: March 2022

EUREC4A is an international project that aims to address the current lack of understanding of the processes controlling the response of trade-wind cumulus clouds to changing environmental conditions in a warmer climate. The radiative properties of the trade-wind cumulus clouds have a major influence on the Earth's radiation budget. The response to global warming of these clouds is therefore critical for global mean cloud feedbacks. The EUREC4A field campaign took place in the vicinity of Barbados during January and February, 2020. The BAS Twin Otter aircraft was deployed in the project to make measurements of aerosols, cloud microphysics and boundary-layer processes in the life cycle of the clouds. In-situ measurements were made of the cloud droplet size distributions and the development of warm rain in multiple cases at different altitudes. We found significant variability in the development of precipitation between cases. The cloud structure appeared to have a significant impact on the precipitation, while the aerosol concentrations in the boundary layer were strongly related to the initial droplet number concentration at cloud base. We will present these findings by highlighting a number of cases with different cloud types and aerosol properties.
Assessment of atmospheric stability measurements from microwave radiometer observations for offshore wind energy applications
Authors: Cimini Domenico , Gandoin Rémi , Fiedler Stephanie , Wilson Hector , Pospichal Bernhard , Martinet Pauline , Balotti Andrea , Gentile Sabrina , Romano Filomena
Published: March 2022

Atmospheric stability is a measure of atmospheric status which determines whether thermodynamically perturbed air will rise, sink, or be neutral. Atmospheric stability has a major impact on the evolution of wind turbine wakes and thus on the yield and performance of offshore wind parks. For estimations of wind park power output and for improving analyses of offshore wind park wakes, a crucial parameter was found to be profiles of atmospheric temperature and stability metrics. Atmospheric temperature profiles can be measured in-situ by balloon-borne sensors, but also estimated from the ground using radiometric observations. This presentation reviews the stability metrics useful for monitoring wind park performances and provides a quantitative assessment of the value of microwave radiometer (MWR) observations to estimate these stability metrics from near surface, either over land or ocean. Results from three different MWR instruments, representing the most common available on the market, and at least three field experiments will be presented.

 

This work has been funded by Carbon Trust and the partner companies of the Off-shore Wind Accelerator program: (in alphabetical order) EnBW, Equinor, Orsted, RWE, Scottish Power Renewables, Shell, SSE Renewables, Total Energies, Vattenfall.
Mathematics & Analysis of a MEMS Semi-Absolute Pendulum Gravimeter
Authors: Walker Richard , Utting Phoebe , Middlemiss Richard , Prasad Abhinav , Hammond Giles
Published: March 2022

This research provides an overview of the mathematics influencing the design of a pendulum-based semi-absolute MEMS (Micro-Electro-Mechanical Systems) gravimeter, currently being developed at the University of Glasgow. The device comprises two pendula actuated in anti-phase, allowing a differential measurement of local gravity that is isolated from seismic noise. The pendula are pivoted about a narrow flexure, and are therefore subject to changes in elastic stiffness with temperature. By adding mass this effect is diluted and the behaviour becomes asymptotically dominated by the gravitational restoring force, reducing temperature sensitivity.

 

The rationale behind the basic topology of the device will first be explained in terms of both the differential representation of the system and the corresponding vibratory profile modelled using finite-element software. This is followed by a brief discussion of the main factors influencing the measurement of gravity such as thermal and damping effects. The primary focus of the research will be how best to model the physics of pendulum motion, how to extract a value for gravity from this model, and the optimum sampling technique required in order to satisfy both device sensitivity and hardware limitations. A comparison between the simulated behaviour and preliminary experimental data will then be made from which the efficacy of the modelling solution can be inferred. Finally, the results of a lift-test, wherein the device is moved to various floors of a building and which is designed to estimate the performance of the device, will be discussed and contrasted with similar data from an existing relative MEMS gravimeter (the 'wee-g'), as well as any projected design modifications considered as a consequence of these results.
A semi-analytical model for marine ice sheet dynamics
Authors: Hewitt Ian
Published: March 2022

Marine ice sheets have the greatest potential to contribute to rapid sea-level change because of the potential for rapid transfer of grounded ice (with thickness above flotation) to floating ice shelves or icebergs.  Ice loss occurs when this transfer (the 'grounding-line flux') is larger than the rate at which ice accumulates over the grounded ice sheet.  It is well known that the balance between accumulation and grounding-line flux can result in both stable and unstable ice-sheet states, and that this leads to the potential for 'marine-ice-sheet-instability' (MISI).   Various reduced mathematical models have been used to examine the stability of steady states, accounting for different parameterisations of basal drag, lateral buttressing and ice-shelf melting/calving.  However, real-world ice sheets are (presumably) rarely in a steady state, since the timescales taken for an ice-sheet to reach steady state are typically thousands of years, longer than the timescales on which the forcing changes.  The time-dependent dynamics are therefore important. 

Here, we detail a simple depth- and width- integrated model for a marine ice sheet that yields insight into the time-dependent dynamics that result from changing climate forcing.  The model - which reduces to a relatively simple dynamical system - demonstrates how gradual changes in forcing (surface accumulation, ocean temperature, for example) cause changes in the 'landscape' through which the ice-sheet evolves.  It reproduces some existing results for how the stability of steady states depends on the topography, as well as new results for the pace of groundling advance and retreat.  Investigating fundamental aspects of the time-dependent dynamics in a simplified model like this is important in order to understand the extent to which ice-sheet changes are 'irreversible' (or not). 
Scientific evidence of the economic benefits of ecosystem-based disaster risk reduction and ecosystem-based climate change adaptation
Authors: Vicarelli Marta , Kang Michael , Leue Madeline , Shrestha Aryen , Wasielewski David , Sudmeier-Rieux Karen , Mysiak Jaroslav , Schütze Simon , Marr Michael , McAndrew Shannon , Vance Miranda
Published: March 2022

Ecosystems and ecosystem services are key to helping achieve reduction in disaster risk, sustainable development, and climate change adaptation, and this is now recognized by major international framework agreements (Convention on Biological Diversity, 2014; United Nations Office for Disaster Risk Reduction, Sendai Framework for Disaster Risk Reduction, 2015-2030). However, there is limited knowledge about the cost efficiency and socio-economic equity outcomes of Nature-based Solutions (NbS) compared to traditional engineered strategies.

In this study we developed a global database of more than 130 peer-reviewed studies, published between 2000 and 2020, that perform economic evaluations of NbS for Ecosystem-based Climate Adaptation (EbA) and Ecosystem-based Disaster Risk Reduction (Eco-DRR). Using meta-analysis techniques, we assess the existing scientific knowledge on the economic viability and performance of NbS for Eco-DRR and EbA, cataloguing outcomes both in terms of degree of economic efficiency and social equity. Our analysis includes multiple dimensions: geographic distribution of the published studies, types of ecosystems and ecosystem services evaluated, hazards and climate impacts analyzed, and economic methodologies used to perform economic efficiency evaluations (e.g., cost benefit analysis, stated/revealed preferences evaluation methods).

This study builds on a recent global assessment (Sudmeier-Rieux et al, 2021) that performs the first systematic review of Eco-DRR peer-reviewed studies across all disciplines. Their results show robustness of evidence and level of agreement on the role of ecosystems in attenuating 30 types of hazards, based on the assessment methodology established by the Intergovernmental Panel on Climate Change (IPCC). Our meta-analysis expands the 2021 review by evaluating the economic benefits associated with Eco-DRR and NbA approaches; by examining cost efficiency of Eco-DRR and NbA interventions compared to traditional engineering solutions; by performing equity assessments of the outcomes; and by studying how the NbS interventions reviewed contributed to the sustainable development goals (SDGs).

REFERENCE:

Sudmeier-Rieux, K., Arce-Mojica,T., Boehmer, H.J., Doswald, N., Emerton, L., Friess, D.A., Galvin, S., Hagenlocher, M., James, H., Laban, P., Lacambra, C., Lange, W., McAdoo, B.G., Moos, C., Mysiak, J., Narvaez, L., Nehren, U., Peduzzi, P1., Renaud, F.G., Sandholz, S., Schreyers, L., Sebesvari, Z., Tom, T., Triyanti, A., van Eijk, P., van Staveren, M., Vicarelli, M., Walz, Y. "Scientific evidence for ecosystem-based disaster risk reduction." Nature Sustainability (2021): 1-8. 
Assessment of Land Surface and Atmospheric Model Mass Flux Using Water Balance Techniques and GRACE/GRACE-FO Data
Authors: Krichman Benjamin , Bettadpur Srinivas , Pekker Tatyana
Published: March 2022

GRACE mission data is used to derive variations in terrestrial water storage in order to evaluate approaches to the water balance. The data in the span of the GRACE and GRACE Follow-On missions is analyzed, and long-term behavior of a variety of basins is characterized. Terrestrial water storage variations are calculated via a combination of flux quantities from land surface models and atmospheric reanalyses using two common water balance approaches as well as a third approach using a novel algorithm for basin boundary discretization. Results are used to evaluate the new approach and form an understanding of its limitations, in relation to both the model data ingested as well as the characteristics of the regions in question.  From the results, we observe significant variations in model performance over diverse geography and climatic conditions, such as diminished accuracy in atmospheric reanalyses under the effect of long term drought. These observations suggest utility as a diagnostic to assess and inform improvement in the studied models.
Joint GNSS-InSAR analysis of ground deformation on the eastern flank of Mount Etna. 
Authors: Carnemolla Francesco , Bonforte Alessandro , Brighenti Fabio , Briole Pierre , De Guidi Giorgio , Guglielmino Francesco , Puglisi Giuseppe
Published: March 2022

Mount Etna is located on eastern Sicily on the border of the collision zone between the Eurasia and Nubia plate. The regional geodynamic framework is characterized by two superimposed regional tectonic domains: a compressional one oriented N-S and an extensional one oriented approximately WNW-ESE. These two domains, together with the volcano-tectonic one, generated a tectonic system which is unique in the world. It exhibits a complex system of faults prevalently on the eastern flank of the volcano, which is the most complicated in terms of interaction between the tectonic, volcano and gravitational processes. The eastern flank of Mount Etna is the most active area of the volcano in terms of deformation and seismicity, because the deformation rates are at least one order of magnitude greater than the surrounding area, due to the eastwards sliding of this flank.

The monitoring and analysis of the high deformation occurring on the eastern flank of Mount Etna is the keystone for understanding the volcano-tectonic dynamics that, apart from the tectonic and volcanic processes, it is paramount relevant because involves the instability of this flank in a densely inhabited area. In this context the Istituto Nazionale di Geofisica e Vulcanologia – Osservatorio Etneo (INGV-OE) created one of the most sophisticated and complete monitoring networks in the world in terms of number of multi-disciplinary station (seismic, geodetic, geochemistry). Since 2014, the GeoDynamic & GeoMatic Laboratory (GD&GM-LAB) of the University of Catania started to create many GNSS sub networks, belonging to the UNICT-Net, in order to determine the offsets occurring on the blocks of each fault of the eastern flank.

In order to have a complete analysis of deformation, INGV-OE and the GD&GM-LAB started to consider this area as an “open-air laboratory” where integrate GNSS and InSAR data with the twofold objective: to characterize the dynamic of this area for contributing to the volcanic hazard assessment and to identify precursor phenomena on shear structures analysing the relationship between kinematics, dynamics and volcano processes in the frame of the ATTEMPT INGV project.