bluuebunny/crossref_metadata_2025 huggingface dataset:
Emission characteristics of atmospheric pollutants from field-scale crop residue burning in Northeast China
Authors: Wang Lili , Wang Qinglu , Cheng Miaomiao , Zhang Tianran , Xin Jinyuan
Published: March 2022

Crop residue burning in china increased significantly in the last decade, especially it took up a majority in Northeast China, which plays an important role of severe haze pollution. Hence, two main types of crop residues (corn and rice straw) were chosen to characterize the particle number concentration, chemical components of fine particulate matter and optical properties of carbonaceous aerosols by a suite of fast-response online portable instruments, together with offline sampling and analysis, during the field-based combustion experiments in Northeast China. For the range of 0.25 and 2.5 µm, more particles were emitted from rice straw burning than those from corn straw burning, and the time-averaged number concentration of particles during the flaming process was approximately 2 times higher than that during the smoldering process for these two straws. Organic carbon (OC), elemental carbon (EC) and water-soluble ions were the most abundant components and accounted for 42.5±7.5%, 7.7±1.7% and 18.0±3.4% of the PM2.5, respectively. Furthermore, rice straw burning emitted higher OC and lower Cl- and K+ than those from corn straw burning. The average absorption Ångström exponent (AAE) of carbonaceous aerosols was 2.1±0.3, while the AAE of brown carbon (BrC) was 4.7±0.4 during the whole burning process. On average, BrC contributed to 63% and 20% of the total light absorption at 375 nm and 625 nm, respectively. Parameterization of BrC absorption revealed that the fraction of absorption from BrC has a reasonably good correlation with EC/OC (-0.84) and AAE (0.94) at 375 nm. Generally, combustion conditions can affect the optical properties of carbonaceous aerosols, and a negative correlation (-0.77) was observed between the AAE and modified combustion efficiency; in addition, the percentage of absorption due to BrC were lower at the flaming phase. To explorer the spatial and temporal variability of open agricultural burning in Northeast China from 2014 to 2019, the emission inventory of key gaseous and particle pollutants was established, which derived from a combination of geostationary (Himawari) and polar (VIIRS) orbiter fire radiative power products. 
Mesoarchean nanogranitoids and fluid inclusions in garnet from migmatites of the Kangerlussuaq basement, Southeast Greenland
Authors: Ferrero Silvio , Nicoli Gautier , Gresky Kerstin
Published: March 2022

Inclusions of anatectic melt and fluids are probes used by geoscientist to investigate, understand and quantify devolatilization, melt production and chemical differentiation during orogenesis and crustal reworking. The large majority of case studies targeting these types of inclusions are in the Phanerozoic eon, whereas the Precambrian is still poorly represented. Here we present the first data on anatectic melt inclusions (nanogranitoids) and their associated primary fluid inclusions in garnets from the Mesoarchean basement in Southeast Greenland. Using optical microscope observations, MicroRaman spectroscopy and microprobe investigation we show that these metasedimentary migmatites contain two generations of garnets, a large xenoblastic garnet (Grt1) and a small idioblastic one (Grt2). Both garnet types contain clusters of primary nanogranitoids which are characterized by the presence of quartz and feldspar polymorphs + phyllosilicates, a phase assemblage typically observed in this type of inclusions. Nanogranitoids are associated in the clusters to primary CO2-CH4 fluid inclusions, which appear to be always affected by post-entrapment modifications with extensive formation of step-daughter minerals such as carbonates and pyrophyllite. Such occurrence proves for the first time that these rocks experienced partial melting with formation of garnet, and that this event took place in presence of COH-rich fluid. The re-evaluation of the metamorphic pressure and temperature conditions with up-to-date phase equilibria modelling, combined with the identification of nanogranitoids and fluid inclusions, suggests metamorphic peak equilibration and partial melting at T> 900 °C and P> 7 kbar. To date, this is the oldest verified occurrence of nanogranitoids as well as of fluid-melt immiscibility during garnet growth in a partially molten environment.
The Jura Fold-and-Thrust Belt: timing and kinematic of faulting and thrusting 
Authors: Mosar Jon , Schori Marc , Borderie Sandra , Hauvette Louis , Marro Adeline , Radaideh Omar , Sommaruga Anna , Ursprung Anina
Published: March 2022

The Jura Mountains in France and Switzerland are a classical thin-skinned fold-and-thrust belt (FTB), which developed as part of the Alpine orogenic foreland, together with the Western Alpine Molasse Basin. The Molasse Basin initiated as a flexural basin and evolved into a wedge-top Basin following the initiation of the main foreland décollement level. The Jura FTB thus forms the frontal portion of the Alpine foreland, which enjoyed a transport of some 30km towards the foreland along the main décollement in the mechanically weak Triassic salt-rich evaporites.

Overall the Jura FTB behaves as a mechanical wedge in hydrostatic conditions, that is propagating towards the Alpine foreland. Wedge-internal accommodations, due to changes in the surface topography and the basal décollement inclination, as well as in the basal friction, are operated by oscillating forward and backward stepping sequences of thrusting and related fold development. Basement topography associated with inherited faults leads to a kinematic preconditioning of the structures developing in the detached cover. Analogue modelling has helped show that oblique steps in the basement topography lead to the formation of normal and reverse faulting and oblique fold structures in the cover.

Herein we will discuss the link of different types of faults observed in the field, such as normal faults, inverted inherited faults, thrust faults and strike-slip faults, to major tectonic processes such as flexural bending, rifting, faulting due to steps in basement topography, and thrusting inside a mechanical wedge.

Works on relative chronology of faults, combined with new results from kinematic section modelling and data on published and new deformation ages from calcites (using U-Pb) make it possible to assess the timing of deformation. It is thus possible to show that thrust faults and strike-slip faults, as well as, normal and inverted faults were active at different times and witness superposed events. Deformation in the Jura FTB is partitioned and distributed along discrete faults that clearly operate in a forward and backward oscillating manner. We further can identify different structural domains that can be considered as distinct tectonic nappes. These domains are bound by major strike-slip faults (acting as inherited, rigid boundaries), progressive en-echelon relay zones and major thrusts. The present-day deformation involving both the detached cover and the mechanical basement will be discussed.
Wave geometry of the stratospheric polar vortex during extreme and moderate El Niño events
Authors: Zhou Xin , Chen Quanliang , Hou Zhaolu
Published: March 2022

This paper examines the differences in the troposphere-stratosphere coupling during extreme and moderate El Niño events by considering the wave geometry of the stratospheric vortex, using two-dimensional moment diagnostics to measure the geometry of the vortex. Based on reanalysis data for 1979–2020 and sensitivity runs with the Whole Atmosphere Community Climate Model version 4 (WACCM4), we demonstrate that the Arctic polar vortex exhibits larger variability throughout the late winter to the early spring season in terms of the vortex geometry during extreme El Niño than that during moderate El Niño. Although both equatorward displacement and splitting of the vortex are detected during moderate and extreme El Niño events, split vortex events show larger occurrences than displaced vortex events in the case of extreme El Niño. This is in agreement with stronger tropospheric responses to extreme El Niño manifested in zonal mean signals in the tropospheric jet stream and surface temperature. The geometric characteristics of the vortex, being incoherent with the zonal mean results, show that disturbed vortex during extreme El Niño penetrate deeper into the troposphere, while anomalies associated with moderate El Niño do not decent far below the tropopause.
Migration lengths of uranium in the Opalinus Clay are determined by the pore water geochemistry and hydrogeological setting
Authors: Hennig Theresa , Kühn Michael
Published: March 2022

Any safety assessment of radioactive waste disposal sites is done based on the simulation of migration lengths of radionuclides through the host formation. This is done by the application of transport parameters obtained from experiments with homogeneous, e.g. geochemically and mineralogically constant, conditions. However, such an assumption of homogeneity is no longer applicable on the host rock scale (>200 m). Consequently, experimentally determined transport parameters might no longer represent the host rock on larger scales.

Uranium, as main component of spent fuel, is used here as an example to evaluate the impact of heterogeneous systems on the total migration lengths compared to homogeneous ones. For this, the hydrogeological system of the Swiss Opalinus Clay, a potential host rock, is modelled in one-dimensional diffusion simulations with PHREEQC. Since sorption and hence migration of uranium is primarily governed by pCO2 > Ca2+ > pH > pe > clay mineral quantity [1], the focus is on the simulation of the geochemically heterogeneity, and thus on the hydrogeological system. Sorption is quantified with mechanistic surface complexation models and cation exchange. At Mont Terri, geochemical gradients established towards the embedding aquifers due to diffusive exchange over millions of years as a consequence of the Jura folding and associated erosion history [2].

First, measured pore water profiles were confirmed by the simulations. They served as starting profiles for the subsequent uranium migration that was quantified in a second step. By comparing migration lengths after a simulation time of one million years with results of homogeneous simulations, it has been shown that uranium migration is enhanced by up to several tens of meters depending on the pCO2. Consequently, the entire hydrogeological system needs to be taken into account and the governing parameters can be prioritized as follows: pCO2 > hydrogeology > mineralogy.

 

[1] Hennig T., Stockmann M. and Kühn M. (2020): Simulation of diffusive uranium transport and sorption processes in the Opalinus Clay. Applied Geochemistry, 123. DOI:10.1016/j.apgeochem.2020.104777.

[2] Mazurek M., Alt-Epping P., Bath A., Gimmi T., Waber H. N., Buschaert S., De Cannière P., De Craen M., Gautschi A., Savoye S., Vinsot A., Wemaere I. and Wouters L. (2011): Natural tracer profiles across argillaceous formations. Applied Geochemistry 26 (7), 1035–1064.DOI:10.1016/j.apgeochem.2011.03.124

 
Multi-risk analysis, mitigation and resilience in historical cities
Authors: Arrighi Chiara , Tanganelli Marco , Cardinali Vieri , Cristofaro Maria Teresa , De Stefano Mario , Castelli Fabio
Published: March 2022

The need for a shift from single to multi-risk analysis is widely recognized in international agreements, however the different multidisciplinary aspects, hazard metrics, data requirements and resolutions make quantitative multi-hazard and multi-vulnerability assessment rarely practiced. This work aims at describing a multi-risk assessment including present and mitigation scenarios and multi-risk resilience for historical art cities where the ability to recovery from a disaster passes through cultural heritage and related economic activities. Earthquakes and floods are considered to introduce a multi-risk workflow for buildings based on common metrics for exposure, vulnerability, and risk and a dynamic resilience model to simulate the post-event recovery. The method is applied to the historical city center of Florence (Italy), which is exposed to low-probability events and renowned for its unique cultural heritage. The application of the method suggests that the estimation of direct physical damages for earthquakes and floods requires a different characterization of vulnerability parameters. The resilience to earthquakes and floods shows significantly different recovery times that are linked to the severity of losses. The results of the application to the historical city center Florence show interesting differences in the spatial distribution of multi-risk, mostly depending on the evolution of the constructive typologies form the Middle-Ages to the XX century but also on the anthropic alteration of terrain morphology.  Further research would be needed to finding synergies in multi-risk mitigation and to better understand resilience to cascade risks.

Arrighi, C., Tanganelli, M., Cristofaro M.T., Cardinali, V., Marra, A.M., Castelli, F., De Stefano M.: Multi risk assessment in a historical city, Natural hazards, doi.org/10.1007/s11069-021-05125-6
Characterising the Triassic Palaeomagnetic Field with an Aim to Investigate the Mesozoic Dipole Low.
Authors: Handford Ben , Biggin Andy , Rapalini Augusto , Haldan Marcela , Langereis Cor , Monti Mariana , López de Luchi Mónica , van der Boon Annique , Franceschinis Pablo , Kugabalan Banusha
Published: March 2022

Palaeomagnetic field behaviour within the Triassic is relatively poorly documented in comparison with other periods from across the last ca 250 Ma. Developing a more complete understanding of the Triassic field has important implications for discussion surrounding the Mesozoic Dipole Low (MDL) and the processes that govern field intensity and reversal regimes. We have conducted the first palaeosecular variation study that incorporates Triassic virtual geomagnetic pole (VGP) data, and analysed this data within the context of the average reversal frequency for the period. We observed remarkably similar VGP dispersion patterns from the late Permian, after the Permo-Carboniferous Reversed Superchron, until the onset of the Cretaceous Normal Superchron, despite fluctuating mean reversal rates. We have also completed palaeointensity experiments on samples with a range of lithologies collected from two localities in Argentina as well as pillow basalts from northern Italy. Previously published radiometric ages place our sampled lithologies across all three Triassic epochs, presenting an opportunity to populate the palaeointensity record at multiple ages across the ~50 Ma lacuna. Results were obtained utilizing a range of methods, the IZZI+ thermal Thellier, Shaw, and pseudo-Thellier. Estimates of virtual dipole moment from these experiments will be presented and discussed in the context of their reliability, and importance in better defining the MDL.
Orogenic evolution of Western Europe controlled by lithosphere evolution
Authors: Mouthereau Frédéric , Angrand Paul , Jourdon Anthony , Ternois Sébastien , Celini Naïm , Lahfid Abdeltif , Callot Jean-Paul
Published: March 2022

Processes driving orogenic styles and long-term isostatic versus dynamic support of the topography have been largely debated in domains of plate convergence. Tectonics of orogens reflect the interactions between mantle flow driving plates and the inherited rheology and composition of moving plates, which are however still strikingly ill-defined. A recent review of the evolution of the weak European lithosphere, based on geological, geophysical, petrological data, has shed lights on the role played by lithospheric mantle chemo-magmatic history and structure, which inherits past subduction/collision (e.g. Variscan) and rifting events (Tethys/Atlantic), on crust-mantle coupling, plate-mantle coupling, defining Alpine-type orogens. While the details of the Cenozoic topographic history of peri-Mediterranean orogens are understood to be controlled by the rheology and architecture of rifted margins combined with changing large-scale kinematic boundary conditions (e.g. Atlas, Betics, Pyrenees, Alps), their post-10 Ma, quaternary to current surface (Insar) and tectonic (seismic) evolution appears to illustrate increasing control by magmatism and flow at the asthenosphere-lithosphere limit as well as local thermal re-equilibration. We argue that isostatic processes in western Europe linked in part to long lithosphere evolution can be first-order drivers of the post-collisional evolution of the peri-Mediterranean orogenic belts and their still active surface and tectonic evolution.
Assessment karstic water origin along South slope of Grate Caucasus Mountain range 
Authors: Vepkhvadze Sopio , Malik Peter , Melikadze George , Todadze Mariam , Ghlonti Ludmila , Tchikadze Tornike
Published: March 2022

The impact of climate change had caused that precipitation has significantly decreased in Georgia which caused significant decrease of surface water flows and depletion of groundwater amounts in natural springs. In the same time, the waters recharged in karstic aquifers, occurring on the southern slopes of the Greater Caucasus Mountains, can be considered as alternative groundwater resources for the communities in lowlands and the adjacent foothills. Here, about half of the renewable groundwater resources in artesian basins and confined groundwater systems in Georgia can be considered as belonging to the above mentioned water-bearing horizon. In order to assess water resources, the pathways between the recharge zones along the Caucasus and aquifers need to be addressed and risks of groundwater contamination along these pathways need to be evaluated.

On the territory of West Georgia, hydrogeological and hydrogeochemical surveys were performed in order to define the main hydrogeological features of the region. In the frame of this research, more than one hundred water sources (springs, wells, boreholes, rivers) were sampled during 2019. Physical parameters (pH, O2, EC, temperature) were measured on site during sampling. Water samples were collected for chemical (major ions) and isotope analysis (18O and 2H). Karstic areas of West Georgia were covered by mapping. Isotopic composition of water in the study area evolves according to a line parallel with the global meteoric water line. Available isotopic data indicate several groups of groundwater types. Some of them very probably represent older waters, with substantially long mean residence time. Samples with pronounced isotope composition variability indicate the evolution of groundwater isotopic composition from the recharge area in the mountains through river valleys to the exfiltration areas. Deuterium excess shows higher values, typical for mountain precipitation and snow in mountain ranges. The conjunctive use of isotopic approaches demonstrates a high potential for future water resources studies in Georgia.
Observations of the Time Domain Sampler receiver from the Radio and Plasma Wave instrument during the Solar Orbiter Earth flyby 
Authors: Pisa David , Soucek Jan , Santolik Ondrej , Hanzelka Miroslav , Maksimovic Milan , Vecchio Antonio , Khotyaintsev Yuri , Chust Thomas , Kretzschmar Matthieu , Matteini Lorenzo , Horbury Timothy
Published: March 2022

On November 27, 2021, Solar Orbiter completed its only flyby of Earth on its way to the following Sun’s encounter in March 2022. Although this fast flyby was performed primarily to decrease the spacecraft’s velocity and change orbit to get closer to the Sun, the Radio and Plasma Wave (RPW) instrument had the opportunity to perform high cadence measurements in the Earth’s magnetosphere. We review the main observation of the Time Domain Sampler (TDS) receiver, a part of the RPW instrument, made during this flyby at frequencies below 200 kHz. The TDS receiver operated in a high cadence mode providing us with the regular waveform snapshot with 62 ms length every ten seconds for two electric components. Besides the regular captures, we have got more than five hundred onboard classified snapshots and the statistical products with a sixteen-second cadence. Before entering the terrestrial magnetosphere around 02:30UT, the spacecraft wandered through the foreshock region, registering intense bursts of Langmuir waves. After the bowshock crossing, Solar Orbiter was for more than two hours in the morning sector of the magnetosphere, recording various plasma wave modes. The closest approach was reached at 04:30UT above North Africa at an altitude of 460 km. Then the spacecraft continued into the Earth’s tail and entered the magnetosheath around 13:00UT. After 15:00UT, the Solar Orbiter crossed the bowshock, and bursts of Langmuir waves were detected again pointing out to the deep downstream foreshock region. Further from the Earth, intense Auroral Kilometric Radiation (AKR) at frequencies above 100 kHz was also detected.
Role of salinity and temperature on the North Brazil Undercurrent
Authors: Liu Hao
Published: March 2022

North Brazil Undercurrent is a western boundary current in the tropical South Atlantic Ocean. It is generally located between 11S and 5S, and it forms as the South Equatorial Current encounters the coast of northern Brazil. It carries a large volume of water and heat and plays an important role in the Atlantic Meridional Overturning Circulation and the South Atlantic Subtropical cycle. We have used three high-resolution and one low-resolution model outputs to explore the linear trend of NBUC transport and its variability on annual and interannual time scales. We find that the linear trend and interannual variability of the geostrophic NBUC transport show large discrepancies among the datasets. Thus, the linear trend and variability of the geostrophic NBUC are associated with the model configuration. We also find that the relative contributions of salinity and temperature gradients to the geostrophic shear of the NBUC are not model-dependent. Salinity-based and temperature-based geostrophic NBUC transports tend to be opposite-signed on all time scales. Despite the limited salinity and temperature profiles, the model results are consistent with the in-situ observations on the annual cycle and interannual time scales. We have highlighted the equally important roles of temperature and salinity in driving the variability of NBUC transport.
Modeling Spatial Extremes Using Normal Mean-Variance Mixtures
Authors: Zhang Zhongwei , Huser Raphaël , Opitz Thomas , Wadsworth Jennifer
Published: March 2022

Classical models for multivariate or spatial extremes are mainly based upon the asymptotically justified max-stable or generalized Pareto processes. These models are suitable when asymptotic dependence is present, i.e., the joint tail decays at the same rate as the marginal tail. However, recent environmental data applications suggest that asymptotic independence is equally important and, unfortunately, existing spatial models in this setting that are both flexible and can be fitted efficiently are scarce. Here, we propose a new spatial copula model based on the generalized hyperbolic distribution, which is a specific normal mean-variance mixture and is very popular in financial modeling. The tail properties of this distribution have been studied in the literature, but with contradictory results. It turns out that the proofs from the literature contain mistakes. We here give a corrected theoretical description of its tail dependence structure and then exploit the model to analyze a simulated dataset from the inverted Brown--Resnick process, hindcast significant wave height data in the North Sea, and wind gust data in the state of Oklahoma, USA. We demonstrate that our proposed model is flexible enough to capture the dependence structure not only in the tail but also in the bulk.
The global and regional structure of simulated historical ocean heat content change in CMIP6 models
Authors: Kuhlbrodt Till , Voldoire Aurore , Killick Rachel , Palmer Matthew
Published: March 2022

Ocean heat content is arguably the most relevant metric for tracking the current global heating. Because of its enormous heat capacity, the global ocean stores about 89 percent of the excess heat in the Earth System. Time series of global ocean heat content (OHC) closely track Earth’s energy imbalance, observed as the net radiative imbalance at the top of the atmosphere. Therefore, simulated OHC time series are a cornerstone for assessing the scientific performance of Earth System models (ESM) and global climate models. Here we present a detailed global and regional analysis of the OHC change in CMIP6 simulations of the historical climate (20th century up to 2014) performed with four state-of-the art ESMs and climate models: UKESM1, HadGEM3-GC3.1-LL, CNRM-ESM2-1 and CNRM-CM6-1. All four share the same ocean component, NEMO3.6 in the shaconemo eORCA1 configuration. Analysing only a small number of models allows us to extend our analysis from a global perspective, to also consider individual ocean basins.

For the global ocean, the two CNRM models reproduce the observed OHC change since the 1960s closely, especially in the top 700 m of the ocean. The two UK models (UKESM1 and HadGEM3-GC3.1-LL) do not simulate the observed global ocean warming in the 1970s and 1980s in the top 700 m, and they warm too fast after 1991. We analyse how this varied performance across the models relates to the simulated radiative forcing of the atmosphere and its components. All four models show a larger transient climate response (TCR) than the CMIP5 ensemble mean.

For the UK models, resolving the ocean warming in depth and time shows virtually zero historical warming at intermediate depths (700 m – 2000 m) whereas the global full-depth OHC change is reasonably simulated. After 1991, regional ocean heat uptake in the North Atlantic plays a substantial role in compensating small warming rates elsewhere.

A different picture emerges from the CNRM models. Globally the simulated OHC change is closer to observations, especially for CNRM-ESM2-1. Regionally the simulated OHC change is close to observations in the Pacific and Indian basins, while tending to be too small in the Atlantic, indicating a markedly different role for the Atlantic meridional overturning circulation (AMOC) and for cross-equatorial heat transport between the CNRM models and the UK models. While the UK models simulate larger than observed historical warming below 2000 m in the Atlantic and South Pacific, the CNRM models take up heat at a larger than observed rate at intermediate depths in the South Atlantic and the South Pacific, with a much smaller role for the North Atlantic in global ocean heat uptake.  
Mid-Infrared Observations of Neptune and Uranus: Recent Discoveries and Future Opportunities
Authors: Roman Michael T. , Fletcher Leigh N. , Orton Glenn S. , Greathouse Thomas K. , Moses Julianne , Rowe-Gurney Naomi , Irwin Patrick G. J. , Kasaba Yasumasa , Fujiyoshi Takuya , Hammel Heidi B. , de Pater Imke , Sinclair James , Antuñano Arrate
Published: March 2022

We present the primary results from our recent analyses of mid-infrared observations of Neptune and Uranus from ground-based telescopes, including VLT-VISIR, Subaru-COMICS, and Gemini-TEXES.  We discuss our recent discovery that Neptune’s stratospheric temperatures appear to be changing dramatically in just the past few years, following decades of cooling.  In contrast, we show that no evidence yet exists of long-term thermal changes in Uranus’ stratosphere, but mid-IR observations of Uranus are still extremely limited. We share new observations from VLT-VISIR, express the need for continued ground-based imaging, and discuss how the James Webb Space Telescope MIRI observations will help greatly advance our understanding of the Ice Giants in the years ahead.  
Spatial and Temporal variability of fingerprint signatures for sediment source apportionment: implications for technique refinement 
Authors: Tang Qiang , He Xiubin
Published: March 2022

Sediment source fingerprinting using a variety of soil tracers has been widely adopted for obtaining reliable sediment source information, which enables efficient catchment soil conservation and sediment management campaigns. But increasing challenges are rising towards the implementation of this technique against the context of complex landscape configurations and diverse human practices. Recent studies have examined and confirmed the within-source and temporal variability of tracer signatures, herein highlighting the “non-conservative” nature of traditional well-recognized tracers. In China, the landscape fragmentation under the household-base land use system, especially in hilly and mountainous regions, has exaggerate this issue. For example, the complex spatial configuration of mosaic land use patches and dynamic inter-season cropping transitions may significantly complicate soil imprinting processes, leading to highly variability of tracer signatures in a single source group even across a relatively small spatial scale, as well as the season changes of tracer signature for a given sampling unit. In response to this potential uncertainty, improvement of sampling strategies (e.g., increase sample number by enhance sample representativeness, repeated sampling to cover different cropping season) could be an potential option for technique refinement.
Influence of climate and atmospheric circulation changes on water balance of Mount Kenya and surroundings
Authors: Messmer Martina , González-Rojí Santos J. , Raible Christoph C. , Stocker Thomas F.
Published: March 2022

Climate over Kenya is rather heterogeneous and exceptionally dry for a region located in the tropics. This is related to various large-scale drivers, such as Lake Victoria, the complex topography, and the vicinity to the ocean. Not only is the climate complex, but also are water resources scarce, and several stakeholders depend on these. Hence, it is important to understand how the climate and particularly precipitation amounts and patterns change under global warming. A special focus should thereby be on Mount Kenya, which provides one of the most important freshwater towers in Kenya. To investigate these changes, we employ the Weather Research and Forecasting (WRF) model V3.8.1 to downscale a 30-year period for the present and the future climate, based on global climate simulations. The present period covers the years 1981–2010, and the future is run under the high-emission scenario RCP8.5 for the years 2071–2100.

Changes in precipitation and temperature are well noticeable in the region of Mount Kenya. The projection indicates an increase in precipitation for the two rainy seasons (March to May, and October to November), while precipitation is reduced in the dry season. As expected, temperatures are projected to increase over all of Kenya, and particularly along the slopes of Mount Kenya in all months. The peak of Mount Kenya reaches temperatures in the future that are found at an elevation of around 3,200 m above sea level (a.s.l.) in the present. This warming can substantially affect the endemic vegetation along the slopes of Mount Kenya. Assuming that the tree line is limited by temperature and not precipitation, as the latter is abundant, it could move from around 3,000 m a.s.l. up to 3,700 m a.s.l. The strong increase in temperature further affects the remaining glacier, which is currently an important water resource during dry months. The projected increase in precipitation over entire Kenya will therefore increase water availability and reduce the fire danger. Nevertheless, the combined increase in temperature and precipitation could affect human and animal wellbeing, as heat stress may be increased.

All these results are based on a single regional and global climate model. Preliminary results indicate that the rainy season is clearly underestimated in the present simulation, compared to simulations obtained by a downscaling of the reanalysis ERA5. This indicates that important components of the atmosphere are not correctly captured by the model. These could include land-atmosphere interactions, misrepresentation of land cover, biases in sea surface temperatures and related changes in the atmospheric circulations. Thus, the atmospheric circulation and interactions with the land surface have to be assessed in further studies.
A Tale of Two Ice Sheets, SSPs, CMIPs and global models: future climate and surface mass balance projections for Greenland and Antarctica
Authors: Mottram Ruth , Boberg Fredrik , Hansen Nicolaj , Langen Peter , Yang Shuting , Larsen Mathias , Rodehacke Christian
Published: March 2022

Surface Mass Balance (SMB) is the key driver of ice sheet mass budget. It delivers the snow that nourishes ice sheets and the surface melt that balances snowfall and, along with ocean interactions, drives ice flow. We here present alternative future projections for both the Greenland and Antarctic ice sheets, driven by two different earth system models (ESMs), EC-Earth and CESM2, for two different emissions pathways (SSP585, 245) and in the case of EC-Earth for two different CMIP versions (EC-EARTH2 inCMIP5 and EC-EARTH3 in CMIP6).

We use the regional climate model (RCM) HIRHAM5 to downscale the global models to 5.5km resolution over the Greenland ice sheet and 12km resolution over Antarctica. HIRHAM5 output is then used to drive a surface mass budget model for both ice sheets.

The matrix of models and scenarios gives us the opportunity to examine how different factors, including atmospheric circulation indices, model resolution, ocean dynamics, sea ice and SMB components affect mass budget and sea level rise estimates over the course of the 21st century. About half the difference between CMIP5 and CMIP6 SMB estimates is related to differences in the scenarios compared to the SSPs and about half is related to differences in the driving models. In addition, we compare with other published downscaled SMB estimates from different RCMs (MAR and RACMO) to assess the envelope of likely ice sheet evolution out to 2100. Both CESM2 and EC-EARTH3 have high equilibrium climate sensitivity, and our study correspondingly shows high ice sheet mass loss particularly from Greenland by the end of the century, in line with other published estimates under high emissions scenarios. Melt is increasingly important in both ice sheets, but especially Greenland over the course of the 21st century and scales by temperature and therefore emissions pathway. All model projections show an increase in precipitation, but internal variability in circulation in the Southern Ocean still dominates the patterns in Antarctica and masks to some extent climate change signal in SMB.

Future work will extend the ensemble of SMB estimate with a direct statistically based method, that allows fast downscaling of ESM output directly to SMB using the Copenhagen Ice Sheet Surface Energy and Mass Balance modEL (CISSEMBEL) and we also present some early preliminary results comparing different downscaling techniques.
Spatial variation of the background solar wind in the Inner Heliosphere
Authors: Biro Nikolett , Opitz Andrea , Nemeth Zoltan , Timar Aniko , Madar Akos , Koban Gergely , Dalya Zsuzsanna
Published: March 2022

The importance of background solar wind is unquestionable as it carries information on the solar surface conditions and has a major role in space weather events. The current solar minimum is a perfect time period for investigations regarding this field, with several space probes providing in-situ measurements.

 

Our aim is to determine the spatial variations in the background solar wind through multi-spacecraft data analysis, including recent missions, such as Parker Solar Probe and Solar Orbiter. We adjust for the radial and longitudinal time-lags between the different spacecraft, then compare their solar wind plasma measurements. The effects of latitudinal differences between the observations is then backmapped to coronagraph imagery. The results will be useful for further analysis of inner heliospheric structures, for the improvement of propagation models, and to support the analysis of out-of-ecliptic solar wind observations.
Giant polygonal Tepee structures discovered in the NE Red Sea - AL Wajh carbonate platform, KSA
Authors: Vahrenkamp Sarima , Panagiotou Marika , Petrovic Alexander , Khanna Pankaj , Chandra Viswasanthi , Vahrenkamp Volker
Published: March 2022

Carbonate tepee structures are believed to initiate through cement growth in shallow marine hardgrounds causing lateral expansion and leading to upward buckling of cemented layers commonly along polygonal boundaries.  They reportedly form in subtidal to supratidal marine settings and are stratigraphically important markers for exposure and cycle boundaries in ancient rock sequences.  Yet in modern carbonate settings only minor occurrences have been reported from the Arabian Gulf in Abu Dhabi and Qatar as well as in Australia.  We have discovered two spectacular fields of giant polygonal tepee structures on Sheybara Island, a part of the Al Wajh carbonate platform in the NE Red Sea, KSA. Satellite and drone data were used to measure the dimensions of polygons. Samples have been collected from three transects and two boreholes for age dating, petrographic and geochemical analysis. The tepee fields cover an area of 420,000 m2 and 130,000 m2, respectively, in the supratidal to intertidal environment on the ocean facing side of the island.  Individual tepees are composed of chaotically superimposed rugged slabs reaching 3-10 cm in thickness.  Tepee ridges range in height from 10-50 cm.  Tepees are aligned along larger structures of well-defined polygonal shapes.  Their diameters range from 5m to 55m (n =100) with the majority having a diameter of 10-25 m (n=69).  Peculiar to many polygons is a central domal buckle with extensional fracture patterns. The tepees have formed in a well-cemented layer of shallow marine bioclastic sand to gravel-sized sediments composed predominantly of coral, red algae, benthic foraminfera, bivalve and gastropod debris that overlie a paleo-reef flat.  Grains are heavily micritized, cemented by clotted micrite and fibrous to acicular rim cements and occasionally covered by lace-like meshes of organic matter, likely indicating microbial activity.  SEM images from tepee samples show evidence for the presence of microbial activity - biofilms, morphologies that strongly resembles filamentous and coccoidal cyanobacteria, and mineralized cyanobacterial mats. Environmentally corrected C14 age data indicate that polygons formed between 3000 to 1000 years before present (b.p.) correlating with a sealevel regression from a mid-Holocene sealevel highstand some 4000 to 5000 years b.p.  Dead and blackened finger corals commonly encrust tepees indicating that the elevated tepee crusts provide preferential seeding for coral colonialization upon re-submergence.
Degassing conditions and effusive-explosive transitions at Guagua Pichincha volcano, Ecuador
Authors: Colombier Mathieu , Bernard Benjamin , Wright Heather , Le Pennec Jean-Luc , Cáceres Francisco , Cimarelli Corrado , Heap Michael J. , Samaniego Pablo , Vasseur Jérémie , Dingwell Donald B.
Published: March 2022

Stratovolcanoes are often characterized by cyclic eruptive activity marked by effusive-explosive transitions between dome-forming and Plinian eruptions. Guagua Pichincha volcano (Ecuador) has been a location of such cyclicity for the past ~2000 years with recurrent Plinian eruptions in the 1st century, 10th century, and CE 1660 which were separated by dome-forming eruptions such as the recent 1999-2001 eruption. Short time-scale shifts in activity between dome-forming, Vulcanian and Subplinian eruptions also occurred repeatedly in the period September to December 1999. These cycles are therefore a prominent example of effusive-explosive transitions at varying timescales. Here, we investigate the reasons for such shifts in activity, by focusing on degassing and outgassing processes within the conduit, and their roles in pressurization and ensuing eruption dynamics. We have coupled a petrophysical and vesicle textural analysis of dacites from the CE 1660 Plinian eruption and the dome-forming, Vulcanian and Subplinian 1999-2001 eruptions, with percolation models in order to better understand the role of degassing on eruptive style. We demonstrate that the transition from dome-forming to Plinian activity correlates with differences in phenocryst content and consequently in inferred bulk viscosity. A lower initial viscosity is inferred for the Plinian case, consistent with faster ascent, closed-system degassing, explosive fragmentation and eruption. In contrast, dome-forming phases are promoted by a higher magma viscosity, with slower ascent enhancing gas escape and microlite crystallization, yielding effusive activity.

 
Dynamics of East Antarctic glaciers from 1937-2017 analyzed using historical aerial expedition images
Authors: Dømgaard Mads , Huiban Flora , Schomacker Anders , Mouginot Jeremie , Bjørk Anders
Published: March 2022

Since the beginning of the 20th century, various countries have carried out expeditions to Antarctica with the aim of claiming territory, reconnaissance as well as capturing aerial images for topographic mapping. Many of these image inventories has since then been forgotten and never used for scientific purposes. We have gained access to a unique dataset of aerial images captured in 1936-1937 as a part of the Norwegian Thorshavn IV expedition surveying and mapping large parts of the East Antarctic coastline. The images have a stereo overlap of approximate 60% and are digitized using a photogrammetry-grade scanner, enabling us to produce the earliest known digital elevation models and orthophotos of Antarctica.

Expanding the observational records of Antarctic glaciers are vital for better understanding and modelling how changes in climatic parameters affects the ice. Currently, we know very little about the behaviour of Antarctic glaciers prior to the 1990s, due to a lack of large-scale observations. Several studies has proven the effectiveness of using digitally-scanned historical aerial images in studying ice mass losses of the pre-satellite era, but very few such studies exist for Antarctica. In this study, we explore Norwegian and Australian historical aerial expedition images collected between 1937 and 1997 to extensively expand the records and provide the earliest regional-scale Antarctic glacier records. The images are processed using structure-from-motion photogrammetry, which enables us to construct accurate, high-resolution digital elevation models and orthophotos. By combining expedition images with modern satellite data, we are creating a unique time-series dataset to study the changes of multiple glaciers along the East Antarctic coastline in Mac Robertson and Kemp Land between 1937 and 2017.
An update to the development of the Wee-g: A high-sensitivity MEMS-based relative gravimeter for multi-pixel applications
Authors: Anastasiou Kristian , Hammond Giles , Paul Douglas , Toland Karl , Prasad Abhinav , Bramsiepe Steven , Passey Elizabeth , Rakoczi Henrietta
Published: March 2022

The measurement of tiny variations of gravity over long time-scales or across the landscape has been of interest for geophysicists and various industries since the development of the first modern gravimeter. The manufacturing cost and overall survey time required with commercial gravimeters, however, limit their potential application. The MEMS gravimeter developed at the University of Glasgow, Wee-g, is a small form-factor, high-sensitivity relative gravimeter under development, with its low cost enabling the potential to be used in a multi-pixel setting, such as the network planned to be installed around Mount Etna under the NEWTON-g project.

Since the previous reporting of the development and assembly of a MEMS based high-sensitivity relative gravimeter for multi-pixel imaging applications (Toland, K et al, EGU2021-13167), significant progress has been achieved towards the goal of achieving multi-pixel imaging. Wee-g field prototypes have been delivered to end users for various projects, including one currently deployed on Mount Etna since summer 2021. The field prototype running on Mount Etna is running in parallel with an iGrav commercial gravimeter to help understand the characteristics of the Wee-g and allow for comparisons with a commercial device. Currently, multiple final design Wee-g devices are being manufactured for delivery, such as for the multi-pixel array as part of NEWTON-g and for various outdoor field trials. 

This presentation will report on the analysis of the field prototype Wee-g device that is currently running on Mount Etna, as well as the progress that has been made in manufacturing multiple Wee-g devices, and the outlook for activities that will be running throughout 2022, paving the way to a more effective and detailed method of gravity surveying.
Quantifying the impact of soil erosion on soil security by using alternative fallout radionuclides 
Authors: García-Gamero Vanesa , Peñuela Andrés , Mas José Luis , Peña Adolfo , Hurtado Bermúdez Santiago , Vanwalleghem Tom
Published: March 2022

Soil erosion by water is a severe problem throughout the world that threatens soil security and the health of water bodies. This problem is aggravated by global climate change, leading to more intense rainfall and drought events. Moreover, soil erosion also intensifies the impacts of drought by reducing the soils' capacity to hold water and maintain sustainable crop yields. This project aims to evaluate the current status and future evolution of soil security in the Guadalquivir basin. For this purpose, we use a combination of predictive modelling and estimations of long-term soil erosion-deposition rates based on field observations and measurements of fallout radionuclide (FRN) tracers in representative catchments. We test and apply a novel method for analyzing 239+240Pu isotopes, that offers a much cheaper way of analysis and hence a potential new standard to estimate long-term soil erosion-deposition rates. Spatially distributed estimations of long-term soil erosion-deposition rates are used to calibrate and evaluate the soil erosion models RUSLE and MMF-TWI which will then be used to assess present and future soil resource status in the catchments of study. Here, we present the preliminary results of this project, particularly the results obtained by the analysis of 239+240Pu  isotopes in an olive grove catchment and how these results compare against the more established 137Cs analysis and estimations of soil truncation based on measurements of the height of olive tree mounds.
New insights into the non-conservative behaviors of nutrients triggering phytoplankton blooms in the Changjiang (Yangtze) River Estuary.
Authors: Wang Mengyu
Published: March 2022

Four research cruises were carried out during March and July in 2015 and 2016 in the Changjiang (Yangtze) River Estuary and the adjacent shelf. Nutrient concentrations (regarded as static parameters) were measured in the surface and bottom waters collected at 86–99 stations over the course of these cruises. In addition, unfiltered seawater samples were incubated onboard for 48 h to measure the potential change rates of nutrients (regarded as dynamic parameters). These parameters can help directly elucidate non-conservative behaviors of nutrients in order to determine whether seawater serves as a source or a sink. Large nutrient sinks (with more negative variation rates) were consistently found at the surface during the two July cruises at the stations just along the outside edge of the turbidity maximum zone near the mouth of the river. Negative rates, although with much smaller magnitudes, were also found in most bottom water samples in July and at both the surface and bottom in March. The high net nutrient uptake rates at the surface in the summer triggered bloom events later at the seaward stations, showing that high net nutrient uptake is the cause and high chlorophyll-a is the consequence of the bloom. Such information about biogeochemical cycling of nutrients and the mechanisms and development of bloom events occurring in large river estuarine and coastal areas could not have been obtained if these static and dynamic parameters had not been studied together.