bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of re-oxygenation of central Baltic Sea sediment; a laboratory study
Authors: Shahabi-Ghahfarokhi Sina , Rahmati-Abkenar Mahboubeh , Jaeger Leonie , Josefson Sarah , Apler Anna , Djerf Henric , Yu Changxun , Åström Mats , Ketzer Marcelo
Published: March 2022

The eutrophication of the deep central Baltic Sea, Baltic Proper, has caused deoxygenation severe consequences for benthic life. To overcome such limitations and spreads of anoxic basins, proposed techniques such as re-oxygenation of anoxic bottom waters are proposed. However, in the case of the Baltic Proper, the effects of oxygenation in the short term are unknown. Therefore, this research focuses on understanding the geochemistry changes in bottom waters' and sediments during the transition from anoxic/hypoxic to oxic conditions. Six sediment cores were retrieved from the northern and southern Baltic Proper (triplicate cores for each location), where bottom waters have dissolved O2 concentrations of ≈0 mg/L. The bottom waters were exchanged with oxygenated Baltic Sea surface waters for 96 hours. The pH, electroconductivity (EC), and metal concentrations in the exchanged water were measured over time in 12 and 24 hours intervals in the experiment cores. The results indicate that the pH of both sites didn't show any significant change in the exchanged bottom waters during the experiment. However, the EC of the bottom waters on average reduced from 15 to 9 µs/m in both sites. In terms of soluble metals/metalloids, As, Ba, Co, Mn, Mo, Rb, Sr, and U were detected in higher concentrations than unoxygenated bottom water from southern Baltic Proper. Manganese and Sr showed the highest released concentrations in both sites in terms of concentration. This study indicates that undesired release of metals from sediment to the water column may occur during re-oxygenation of Baltic Sea bottom waters. The next stage of this research will focus on the metal transfer from the surface sediments to the bottom waters over the 4-day experiments. This will be done via a sequential chemical analysis scheme, in which surface sediment samples from the experiment will be compared to reference cores collected at the same time as the experimental cores were collected.
Water vapor isotopic signature along the EAIIST traverse
Authors: Casado Mathieu , Leroy-Dos Santos Christophe , Fourré Elise , Favier Vincent , Agosta Cécile , Arnaud Laurent , Prié Frédéric , Akers Pete D. , Janssen Leoni , Kittel Christoph , Savarino Joel , Landais Amaelle
Published: March 2022

Stable water isotopes are a tracer of hydrological processes and a paleoclimate proxy from ice core records. The interpretation of the latter relies on fractionation processes throughout the hydrological cycle, from the evaporation over the ocean, during each precipitation event, and during post-deposition processes, in particular due to the exchanges between the snow and the moisture in the atmosphere. Thanks to new developments in infrared spectroscopy, it is now possible to monitor not only the snow isotopic composition but also the vapour continuously, and thus document exchanges between the snow and the vapour. On the East Antarctic Plateau, records of water vapour isotopic composition in Kohnen and Dome C during summer have revealed significant diurnal variability which can be used to address the exchange between surface snow and atmospheric water vapour as well as the stability of the atmospheric boundary layer. 

In this study, we present the first vapour monitoring on a transect across East Antarctica for a period of 3 months from November 2019 to February 2020 during the EAIIST traverse, covering more than 3600 km. In parallel, we also monitored the vapour isotopic composition at two stations: Dumont D’Urville (DDU), the starting point, and Dome C, half way through. Efforts on the calibration on each monitoring station, as well as cross-calibration of the different instruments offer a unique opportunity to compare both the spatial and temporal (diurnal variability or at the scale of several days) gradients of humidity, temperature and water vapour isotopic composition in East Antarctica during the summer season. 

With the use of the Modele Atmospherique Régional (MAR), we compare the variability measured in water vapour isotopic composition, temperature and humidity with the different systems (fixed or mobile location). Although further comparisons with the surface snow isotopic composition are required to quantify the impact of the snow-atmosphere exchanges on the local surface mass balance, these three simultaneous measurements of the vapour isotopic composition show the potential of using water stables isotopes to evaluate hydrological processes in East Antarctica.  
Tunnel deformation rate analysis based on PS-InSAR technique and stress-area method  
Authors: Chai Long , Xie Xiongyao , Li Pan , Zhou Biao , Zeng Li
Published: March 2022

The permanent scatterer synthetic aperture radar interferometry (PS-InSAR) technique can detect the permanent scatterers(PSs) on the ground. But the deformation of PSs can’t be used to analyze the deformation of underground buildings below the ground surface directly, such as tunnels. In this paper, the process of tunnel deformation analysis using PSs data and stress-area method is proposed. The deformation data of PSs are used to fit the surface deformation of tunnel by kriging interpolation method. The stress area method is used to calculate the deformation of the soil above the tunnel, then the deformation of tunnel can be acquired. This process was applied to calculate the deformation of a tunnel in Shanghai, China. The results show that the fitted surface deformation rate data are accurate, with the maximum absolute difference of 1.45mm/y and the minimum difference of 0.11mm/y compared with the level monitoring data. The tunnel deformation rate calculated by this process is close to the measured deformation rate of the tunnel with error level in millimeters. The surface and tunnel deformation rate curves are similar in the tunnel extension direction. PS-InSAR technique has the advantages of acquiring large area, historical data of surface deformation. Combined with the process proposed in this paper, Large-scale tunnel deformation analysis can be achieved.
Upper ocean mixing from shear microstructure and density inversions nearthe Walvis Ridge
Authors: Roscelli Letizia , Mertens Christian , Walter Maren
Published: March 2022

The M180 cruise is part of the observational program of the TRR 181 'Energy Transfers in
Atmosphere and Ocean', and will focus on observe numerous energy compartments in
order to construct a regional oceanic energy budget for the southeast Atlantic. The study
area will be nearby the Walvis Ridge, a region of strong eddy activity and internal tides, in
the Eastern South Atlantic (0 -10 E, 30 -35 S). There, energy is converted from barotropic
to baroclinic tides at the seafloor. Additionally, in this region, the Agulhas leakage regularly
sheds eddies from the Agulhas current in the form of Agulhas rings that propagate slowly
northwestward. The location is, therefore, ideal for the study of interaction and links
between different energy compartments in the ocean and at the ocean-atmosphere
boundary.
The work will focus on energy dissipation and diapycnal mixing which, on the smallest
scales, drive the circulation in the ocean and is thus of highly significant for the global
meridional overturning circulation in the ocean and its deep ventilation. Time series
microstructure stations will be used to assess locally the temporal variability of mixing
and dissipation. From temperature, density and shear profiles obtained with a Vertical
Microstructure Profiler (VMP-250-IR), it will be possible to calculate the energy dissipation
rate of turbulent kinetic energy by assuming a statistically valid linear relationship
between the Thorpe Scale and the Ozmidov Scale. A direct comparison between the
inferred estimation of the dissipation rate and the directly calculated dissipation rate will
be presented. Moreover, in case a possible influence from Agulhas rings on dissipation is
detected, it will be investigated.
Through which pathways can earthworms increase soil phosphorus availability?
Authors: Van Groenigen Jan Willem , Vos Hannah M.J. , Hiemstra Tjisse , Koopsman Gerwin F.
Published: March 2022

In the search for a more sustainable form of agriculture, a better recycling of major nutrients is essential. For phosphorus (P), one of the most limiting factors to better recycling is chemical adsorption to reactive soil particles, which seriously restricts P supply to plants in many soils. It has been known for some time that earthworms can temporarily increase soil P availability in their casts. However, the exact pathways behind this effect are unclear, making it difficult to infer under which conditions earthworms may significantly contribute to P recycling. In two greenhouse experiments, we studied the occurrence of earthworm-induced increased P availability (i) across a range of common earthworm species; and (ii) across four soils with different physico-chemical characteristics. In the first experiment we analyzed casts of eight common Dutch earthworm species for P pools and related soil properties. For all species, pH in casts was higher than in the bulk soil (up to 1.6 pH unit). Dissolved Organic Carbon (DOC) concentrations were an order of magnitude higher in the casts, and directly available P (defined as water-soluble ortho-phosphate) up to two orders of magnitude. Although these effects were significant for all earthworm species, significant changes were found between the species that could not be explained by conventional earthworm feeding guilds. In the second experiment, we tested effects of three different earthworm species across four soils differing in texture, metal oxide composition, P availabilty and pH. We found a significant effect of earthworms on P availability in all soils, but the extent of this effect varied. Using surface complexation modeling we evaluated the relative importance of the various possible mechanisms. We concluded that the effect of pH on P desorption was relatively small. Increased mineralization of organic P did play an important role; as did competitive desorption of DOC to metal oxides. However, our study also showed a new important pathway: a reduction in reactive surface area of soil metal (hydr)oxides during earthworm gut passage. As this decrease was important in iron (hydr)oxide-dominated soils but not in aluminum (hydr)oxide-dominated soils, we suggest that earthworms have the largest potential to affect soil P availability in the former soils.
Collaborative use of ground monitoring and GPR data for the control of ground settlement in shield tunnel in soft soil
Authors: Li Kang , Xie Xiongyao , Zhang Xiaobin , Zhou Biao , Qu Tenfei , Zeng Li
Published: March 2022

In recent years, China's construction demand for shield tunnel in soft soil continues to increase, and the control of ground settlement in tunnel boring process affects the safety of the tunnel itself and its superstructure directly. Paying close attention to controlling the strata loss and the ground settlement by multiple means is important to ensure construction safety. In this paper, the intelligent real-time monitoring system with dual-frequency ground penetrating radar (GPR) is used to detect the quality of back-fill grouting of shield tunnel, while monitoring points are arranged on the ground surface to acquire the settlement values in real time. The collaborative analysis of ground and underground monitoring results reveals the relationship between grouting and settlement values, and realizes the dynamic guidance on grouting operation, which helps to achieve the purpose of controlling ground settlement better. Last but not least, this paper proposes an outlook on a multiple-data fusion system based on cloud computing platform to adapt to more complex and multiple data in the future, so as to achieve the higher accuracy, efficiency and intelligence of monitoring data analysis.
No channel flow in the Longmen Shan: evidence from the Maoxian-Wenchuan fault Cenozoic kinematics (SE Tibet)
Authors: Ge Chenglong , Leloup Philippe Hervé , Zheng Yong , Li Haibing
Published: March 2022

The NE striking Longmen Shan (LMS) mountains are located at the eastern margin of the Tibetan plateau, and towers nearly 5000m above the Sichuan basin, which is considered to be the greatest relief than anywhere else around the plateau. From west to east, three major sub-parallel faults straddle the Longmen Shan: Wenchuan-Maoxian fault (WMF), Yingxiu-Beichuan fault and Guanxian-Anxian fault. Several models have been proposed to explain the Cenozoic uplift of the Longmen Shan. The major two models are lower crustal channel flow and upper crustal shortening, which imply different movement sense on the Wenchuan-Maoxian fault. The former suggests that the LMS were uplifted above a lower crustal flow expulsed from below the Tibetan plateau and would require a normal sense movement on the MWF. The latter implies that a series of upper crustal thrusts controlled the uplift of the LMS, and the WMF should have a reverse sense. Here we present field observations, fault gouge structural analysis and authigenic illite K-Ar geochronology data of fault gouge in the Wenchuan-Maoxian fault, showing that the Maoxian-Wenchuan fault was dextral with a reverse component at ~7Ma. Reconstruction of offsets of river valleys along the Wenchuan-Maoxian fault suggests that the corresponding total horizontal dextral offset is ~25km. Analysis of the thermochronology data acquired on both side of the fault suggest that dextral-reverse faulting started at ~13 Ma and possibly lasted until today. Our conclusions support the upper crustal shortening model and suggest the channel model maybe not applicable to Longmen Shan uplifting in the Miocene.
Multi-stage late- and post-orogenic deformation history of the innermost Hellenic fold-and-thrust belt from a detailed paleostress reconstruction (Koziakas-Itamos Mts., Western Thessaly, Central Greece) 
Authors: Neofotistos Petros , Tranos Markos
Published: March 2022

The NNW-SSE trending Koziakas-Itamos Mts of Western Thessaly, Central Greece, constitute the innermost part of the External Hellenides, i.e., the Hellenic fold-and-thrust belt, formed from the Tertiary orogenic (alpine) processes due to collision between the Apulia and Eurasia plates. Along these mountains, large ophiolite masses have thrust towards WSW over Mesozoic carbonate and clastic rocks, which in turn thrust over the Tertiary flysch rocks of the Pindos Unit. The mountains bound the NW-SE trending late-alpine Mesohellenic Trough to the east, filled with Late Eocene to Miocene molasse-type sediments, and the younger Thessaly basin filled up with Neogene and Quaternary sediments.

 

A detailed paleostress reconstruction based on the fault-slip analysis and the stress inversion through the TR method (TRM) unravels a multi-stage deformation history for the innermost parts of the Hellenic fold-and-thrust belt. More precisely, the late orogenic faulting deformation temporally constrained in Late Oligocene to Middle Miocene was originally driven by stress regimes that define an ENE-WSW ‘real’ compression normal to the orogenic fabric associated with mainly NE-directed back thrusts. The compression shifted to ‘hybrid’ with the activation of oblique- and strike-slip faults. After that stage, the hybrid compression predominates with counterclockwise changes in the trend of the greatest principal stress axis (σ1) from ENE-WSW to NNE-SSW. The last stage of the late-orogenic faulting deformation is an NW-SE orogen parallel extension segmenting and differentiating the NNW-SSE orogenic fabric along its strike.

 

Post-orogenic faulting deformation is driven by extensional stress regimes that caused the basin-and-range topography and the formation of well-established basins filled up with Late Miocene and younger sediments like the Thessaly basin. In particular, an ENE-WSW pure extension normal to the orogenic fabric has been defined. A general counterclockwise rotation of the least principal stress axis (σ3) occurred, initially giving rise to NE-SW  extension-transtension during Late Miocene-Pliocene and NNE-SSW extension-transtension since the Quaternary.
The role of the stratosphere in understanding future climate change
Authors: Maycock Amanda C.
Published: March 2022

Over the last two decades a growing body of literature has shown that stratospheric processes play a key role for near- and long-term projections of surface climate under different scenarios for anthropogenic and natural forcings. The effect of the stratosphere on surface climate change occurs through two main interconnected pathways: 1) stratosphere-troposphere dynamical coupling; 2) radiative feedbacks predominantly through changes to stratospheric composition. This talk will give some examples of both of these pathways relevant to climate change in the northern and southern hemispheres. Topics will include the role of the strength of the polar vortices for midlatitude circulation change, the stratospheric water vapour feedback and ozone-climate coupling. Two further factors will be discussed that affect how stratospheric processes contribute to surface climate projections: 1) the role of the annual cycle and 2) model biases. In conclusion some thoughts on key future research questions will be offered.
Improving 0-24 h offshore wind power forecasts over the Baltic Sea: comparing post-processing methods of varying complexity
Authors: Hallgren Christoffer , Ivanell Stefan , Körnich Heiner , Vakkari Ville , Sahlée Erik
Published: March 2022

Accurately forecasting short-term wind power production is a challenging task. As the share of wind power in the electrical system is rapidly growing, this task is becoming increasingly important not only for power production companies but also for transmission system operators. By applying post-processing methods to forecasts of wind speed from numerical weather prediction (NWP) models, power production forecasts can be improved. In this study, we used two years of lidar measurements of the wind speed from a coastal site in the Baltic Sea to calculate a theoretical power production and evaluated forecasts from the NWP model HARMONIE-AROME. Six post-processing methods of varying degree of complexity were implemented and tested in order to mimic how they could be used operationally. The performance of the methods in different weather situations was analysed in terms of the mean absolute error (MAE) skill score. For the test period it was found that, in general, the simple method of temporally smoothing the wind speed forecast by applying a low-pass filter (moving average) with a window of ±1 h outperformed the other methods tested. The main reason for this being a reduced risk of double penalty due to small time shifts in wind speed variations in the forecast compared to the observations. However, under weak synoptic forcing the best skill score was achieved using a mix of the forecast from the previous and the current day. Additionally, when low-level jets were forecasted, the best result was achieved using the machine learning random forest algorithm.
Measuring Instantaneous Velocity Fields Remotely using a Two-Dimensional Power Spectral Density Technique
Authors: Johnson Erika
Published: March 2022

A remote method of measuring surface and near-surface currents in wavy riverine environments
at high spatial and temporal resolution is presented. A two-dimensional power spectral density
technique (2D PSD), which is based on calculating the cross-spectrum between two images is
developed and compared with the established 3D PSD technique. In contrast to the 3D PSD
technique, the 2D PSD algorithm is capable of determining velocity time series and spectra,
thereby facilitating remote measurements of turbulence. Moreover, the 2D PSD algorithm can
accurately determine near-surface flows from fewer images. Results are presented from imagery
collected from an unmanned aerial vehicle and satellite imagery from a number of different
riverine locations.
Assessment of parameters describing the signal delay in the neutral atmosphere derived fromVGOS observations
Authors: Haas Rüdiger , Johansson Jan , Elgered Gunnar , Diamantidis Periklis-Konstantinos , Nilsson Tobias
Published: March 2022

Since 2019 observing sessions with the VLBI Global Observing System (VGOS) have been performed
on a regular basis at the Onsala Space Observatory. VGOS is the next generation VLBI system for
geodetic and astrometric VLBI which is in its build-up phase. By 2022 the network has reached 10
stations. VGOS was designed with the goal to improve the accuracy and precision of the geodetic
parameters by one order of magnitude compared with the so-called legacy S/X VLBI system. One aspect
in this context is the ability to resolve small-scale and rapid variations in the signal propagation delay
caused by the neutral atmosphere, which had been identified as one limiting factor of geodetic VLBI.
VGOS addresses this topic by performing many observations per time unit that cover the local sky at
the stations as uniformly as possible. To achieve this, VGOS makes use of small and fast radio telescopes
with reasonably high sensitivity and backends with high sampling capability and relatively large
bandwidths. Currently, at least a factor of two in the number of observations per station is achieved
within the operational VGOS compared to legacy S/X, and future VGOS sessions will have an even
larger number of observations. We assess the current ability of VGOS to sense small-scale, rapid variations in the signal propagation
delay caused by the neutral atmosphere. We compare the VGOS-derived results to corresponding results
from simultaneous observation with co-located instrumentation.
Sources, concentrations and fluxes of mercury wet deposition on the territory of Russian Arctic (a case study in Yamal-Nenets Autonomous Area)
Authors: Eyrikh Stella , Shol Liliya , Shinkaruk Elena
Published: March 2022

In some areas of the Russian Arctic pronounced manifestations of thermal degradation of the permafrost are observed, which can cause an increase in the mercury input into the atmosphere of the Arctic and its further distribution in terrestrial and aquatic ecosystems. Wet scavenging by precipitation events is one of the main ways of Hg removing from the atmosphere. Here we present a study of Hg in wet precipitation on the territory of the Yamal-Nenets Autonomous Area (YNAA) based on the data obtained at the Nadym monitoring stations. Seasonal and annual volume-weighted concentrations (VWC) and fluxes of Hg were determined to assess differences in cold and warm periods and factors influencing these changes. The maximum values in wet precipitation samples were found in the spring, most likely associated with the AMDE phenomenon that contributed from 9.8% to 16.7% in the total annual wet precipitation.

The average annual VWC in wet atmospheric precipitations in Nadym is comparable with the values obtained for other urbanized regions of the world; however, it is much higher than the values reported for remote Arctic places. On the other hand, the annual flux of mercury deposition in Nadym is comparable to remote areas of the Arctic zone but less than annual fluxes in continental-scale monitoring networks of other parts of the world.

There are several main possible sources of mercury in the YNAA: transboundary transport with air masses, regional atmospheric emissions of mercury from fires, and significant regional and local inputs from gas and oil combustion by power plants and factories. In addition, since air temperature and the thickness of the seasonally thawed layers were raised substantially in 2018, the increase of Hg flux in the warm period might also reflect regional input due to the re-emission of Hg from soils.

Keywords: mercury; Arctic; atmospheric wet precipitation; deposition fluxes; AMDE; permafrost thawing.
Gravity wave generation by shear instability of balanced flow
Authors: Chouksey Manita , Eden Carsten , Olbers Dirk
Published: March 2022

The generation of internal gravity waves from an initially geostrophically balanced flow is diagnosed in non-hydrostatic numerical simulations of shear instabilities for varied dynamical regimes. A non-linear decomposition method up to third order in the Rossby number Ro is used as the diagnostic tool for a consistent separation of the balanced and unbalanced motions in the presence of their non-linear coupling. Wave emission is investigated in an Eady-like and a jet-like flow. For the jet-like case, geostrophic and ageostrophic unstable modes are used to initialize the flow in different simulations. Gravity wave emission is in general very weak over a range of values for Ro. At sufficiently high Ro, however, when the condition for symmetric instability is satisfied with negative values of local potential vorticity, significant wave emission is detected even at the lowest order. This is related to the occurrence of fast ageostrophic instability modes, generating a wide spectrum of waves. Thus, gravity waves are excited from the instability of the balanced mode to lowest order only if the condition of symmetric instability is satisfied and ageostrophic unstable modes obtain finite growth rates.
How can contemporary climate research help understand epidemic dynamics? -- Ensemble approach and snapshot attractors
Authors: Kovács Tamás
Published: March 2022

Standard epidemic models based on compartmental differential equations are investigated under continuous parameter change as external forcing. We show that seasonal modulation of the contact parameter superimposed upon a monotonic decay needs a different description from that of the standard chaotic dynamics. The concept of snapshot attractors and their natural distribution has been adopted from the field of the latest climate change research. This shows the importance of the finite-time chaotic effect and ensemble interpretation while investigating the spread of a disease. By defining statistical measures over the ensemble, we can interpret the internal variability of the
epidemic as the onset of complex dynamics—even for those values of contact parameters where originally regular behaviour is expected. We argue that anomalous outbreaks of the infectious class cannot die out until transient chaos is presented in the system. Nevertheless, this fact becomes apparent by using an ensemble approach rather than a single trajectory representation. These findings are applicable generally in explicitly time-dependent epidemic systems regardless of parameter values and time scales.
The Super Atlantic Niño of 2021
Authors: Keenlyside Noel
Published: March 2022

In 2021 there was an exceptionally strong Atlantic Niño—stronger than the last major event in 1996. Positive SST anomalies developed in May and peaked in June-August. There was a build up of heat content in the spring in the western north Atlantic that could be related to local wind stress curl anomalies.  The event appears to have been triggered by zonal wind anomalies in April and May in the western equatorial Atlantic, when strong rainfall anomalies were also observed along the equator. The event terminated with rainfall anomalies shifting northward in late summer. Interestingly, there was also a strong Benguela Niño that developed already in April and has persisted into boreal summer. Furthermore, the event may have contributed to the La Niña event that developed later in the year in the Pacific.
A comparative analysis of urban environmental quality of developing cities of India: A geospatial approach
Authors: Singh Srashti , Jain Kamal
Published: March 2022

Excessive growth in the global human population and eventually urbanisation has become a serious threat to the environment. These situations arise especially in the rapidly developing nations, India being one of them. A higher population naturally poses a high pressure on the environment directly or indirectly, which is a threat for the sustainable development of the country. Most Indian cities face environmental sustainability challenges. Most cities in India are presently going through rapid urbanization and industrialization which leads to environmental degradation of the city. The objective of this study is to analyse the environmental quality of the selected developing cities and also compare the intensity to which they are affected by urbanisation. The study is performed using satellite-based remote sensing data. Initially, Landsat data is used for the years 2001 to 2021 and is utilized for studying the LULC (land use land cover) transformations. MODIS data products are used at 1 km resolution to extract the biophysical indicators (BI) such as normalized difference vegetation index (NDVI) and land surface temperature (LST). MODIS data for PM2.5 is also utilised and finally, an index is calculated to represent the comprehensive environmental quality of the selected cities (CEQI). The yearly and decadal changes in the values of this index is mapped. The LULC transformations depicted a phenomenal decay in the greenness and an increase in the urban built-up area of the city. The CEQI variations and temporal trends reveal the significant deterioration of the overall environmental conditions in most of the cities. This is due to the change in gentrification patterns and also the change in urbanization and the greenness of the city. The study suggests that emission control strategies and urban greening can significantly contribute to enhancing urban environmental quality, especially in rapidly developing cities. The measures suggested to improve the environmental quality can help the policy-makers in the sustainable planning of the city.
Do anomalously high Vp/Vs exist in porous reservoir rocks?
Authors: Pimienta Lucas
Published: March 2022

Anomalously high seismic P- to S-wave velocity ratios (Vp/Vs) have been observed in subduction zones, in locations where varieties of earthquakes and slips are expected to occur, interpreted as highly pressurized heavily fractured zones. Assuming the rocks isotropic, Vp/Vs can be directly linked to rocks Poisson’s ratio in the elastic regimes relevant to both the field and laboratory measurements. From dedicated measurements across the frequency range it was shown that such insights hold, in agreement with a micromechanical model for isotropic micro-cracked rocks: Anomalously high Vp/Vs exist for any low porosity isotropic rocks of any mineral content, if heavily micro-fractured and at near-lithostatic fluid pressures, i.e. at very low Terzaghi effective pressure.

Extending that understanding, one could question if such anomalous Vp/Vs could also be observed and similarly explained in isotropic porous reservoir rocks. From the typical micromechanical inclusion models for predictions at the sample’s scale, such is unlikely as Poisson’s ratio should largely decrease with an increasing content of spherical pores. Yet, that is not what is measured in the relevant undrained elastic regime in well-cemented porous sandstones. For these, most rocks Poisson’s ratio remain anomalously high and comparable to that retrieved in low porosity rocks. Moreover, while models would then predict a dependence of Poison’s ratio to the liquid’s bulk modulus that is again not consistent with the measurements.

From comparing literature datasets reporting drained and undrained Poisson’s ratio and bulk modulus for sandstones of varying porosity, the aim of this work is to investigate and discuss (i) how the measured properties compare, (ii) if one property or the two deviate from existing models and why.
Thermodynamics of the proton plasma in the inner heliosheath during the 24th solar cycle
Authors: Livadiotis George
Published: March 2022

Space plasmas reside in non-equilibrium stationary states described by kappa distributions. The high-energy asymptotic behavior of kappa distributions leads to a power-law relationship of the energy-flux spectra; this relationship, when observed, can be analyzed for determining the thermodynamic parameters of the plasma. In the presented analysis, we use Energetic Neutral Atom (ENA) observations from the IBEX-Hi sensor, converted to the corresponding proton plasma spectra of the inner heliosheath, and timestamped with the ENA creation time. We, then, model the proton spectra with kappa distributions and derive the sky maps of the (radially averaged) values of temperature, density, kappa, and other thermodynamic parameters of the proton plasma in the inner heliosheath. We examine the variations of the determined thermodynamics and whether a correlation exists with solar activity during the 24th solar cycle.
The 2022 Tonga tsunami in the marginal seas of the northwestern Pacific Ocean
Authors: Tsukanova Elizaveta , Medvedeva Alisa , Medvedev Igor , Ivelskaya Tatiana
Published: March 2022

The Hunga Tonga volcanic eruption on 15 January 2022 created a tsunami affecting the entire Pacific Ocean. The observed tsunami was found to have a dual mechanism and was caused both by the wave incoming from the source area and by an atmospheric wave propagating with the speed of sound. The tsunami was clearly recorded in the marginal seas of the northwestern Pacific, including the Sea of Japan, the Sea of Okhotsk and the Bering Sea, in particular on the coasts of Kamchatka, the Kuril Islands and the Aleutian Islands. We examined high-resolution records (1-min sampling) of about 50 tide gauges and 15 air pressure stations in these seas for the period of 14-17 January 2022. On the Russian coast, the highest wave with a trough-to-crest wave height of 1.4 m was recorded at Vodopadnaya, on the southeastern Kamchatka Peninsula; on the coasts of the Aleutian Islands the tsunami waves were even higher, up to 2 m. Based on numerical modelling we estimated the arrival time of the gravitational tsunami waves from the source. We revealed that the character of sea level oscillations for most of the stations evidently changed before these waves arrived. A comparative analysis of sea level and atmospheric data indicated that these changes were probably caused by the atmospheric waves generated by the volcanic eruption.
Modeling low-frequency Rayleigh waves excited by the Jan. 15, 2022 eruption of Hunga Tonga-Hunga Ha’apai volcano
Authors: Zhang Shenjian , Wang Rongjiang , Dahm Torsten
Published: March 2022

Low-frequency seismic energy whose spectrum is centered at certain narrow bands has been detected after violent volcano eruptions. Normal-mode analysis related this signal to the resonances between the atmosphere and the solid earth.
After the powerful eruption of Hunga Tonga-Hunga Ha’apai volcano on Jan. 15, 2022, this low-frequency signal is found on long period and very long period seismometers worldwide. The amplitude spectrum of the signal for this eruption consists of three clear peaks locating at 3.72, 4.61 and 6.07 mHz, instead of two distinct bands for previous cases. The spectrogram analysis shows that this low-frequency energy lasts for several hour and is independent of air wave arrival, while the cross-correlation result confirms that the signal travels as Rayleigh waves with a speed of 3.68 km/s. In this study, we summarize our findings on the observation, and show our synthetic waveforms to provide a possible explanation for the source of this signal. We suggest that the atmospheric oscillations near the volcano excited by the eruption act as an enduring external force on the surface of the solid earth, and produce Rayleigh waves propagating all over the world.
The 15 January 2022 Hunga Tonga event: Using Open Source to observe a volcanic eruption on a global scale in near real time
Authors: Eckel Felix , Garcés Milton , Colet Meritxell
Published: March 2022

The explosive eruption of the Hunga Tonga-Hunga Ha’apai volcano on 15th of January 2022 impacted the Earth, its oceans and atmosphere on a global scale. Witnesses report an audible “bang” as a result of the event in distances of up to several thousand kilometers. With infrasound sensors this sound wave can be detected where the frequency content or the amplitude of the signal renders the event inaudible to the human ear. Infrasound sensors are distributed globally, a selection of these stations upload their data in real time to publicly available servers. In combination with Open Source libraries such as obspy or scipy it is possible to use these data sources to observe the atmospheric disturbances caused by the eruption on a global scale in near real time. With a minimum of data processing not only the first arrival peak of the atmospheric lamb wave can be identified at most stations but also further passes of the wave as it propagates around the planet several times. Having large amounts of publicly available data is crucial in that process. New data chunks can be analyzed and displayed immediately while the signal is still ongoing because data access requests are not required. Additionally, having immediate access to a large dataset allows for big data analysis and reduces the necessity to consider outliers at individual stations and increases the chance to identify the signal after multiple days when overall signal to noise ratios have decreased.
Post-2015 caldera morphology of the Hunga Tonga-Hunga Ha’apai caldera, Tonga, through drone photogrammetry and summit area bathymetry
Authors: Stern Sönke , Cronin Shane , Ribo Marta , Barker Simon , Brenna Marco , Smith Ian E. M. , Ford Murray , Kula Taaniela , Vaiomounga Rennie
Published: March 2022

In December 2014, eruptions began from a submarine vent between the islands of Hunga Tonga and Hunga Ha’apai, 65 km north of Tongatapu, Tonga. The “Hungas” represent small NW and NE remnants of the flanks of a larger edifice, with a ~5 km-diameter collapse caldera south of them. The 2014/15 Surtseyan explosive eruptions lasted for 5 weeks, building a 140 m-high tuff ring.

Deposits on Hunga Ha’apai and tephra fall on Tongatapu record two very large magnitude eruptions producing local pyroclastic density currents and tephra falls of >10 cm-thick >65 km away. These likely derive from the central edifice/caldera. The 2022 eruption produced slightly less tephra fall, but an extremely large explosive event, with regional tsunami indicating substantive topographic change.

Here we report the bathymetric details of the caldera as of November 2015. A multibeam sounder (WASSP) was used to mapping the shallow (<250 m) seafloor concentrating on the edges of the Hunga caldera. These results were combined with an aerial survey of the 2015 tuff cone, using a combination of drone photogrammetry and real-time kinematic GPS surveys. The bathymetry reveals that previous historical eruptions, including 1988 and 2009, and likely many other recent unknown produced a series of well-preserved cones around the rim of the caldera. Aside from the raised ground in the northern caldera produced by the 2009 and 2014/15 eruptions, the southern portion is also elevated to within a few m below sea level, with reefs present. During the 2015 visit, uplifted fresh coral showed that inflation was ongoing and that the caldera was likely in the process of resurgence.

Much of Hunga Tonga and the 2014/2015 cone was destroyed in the 2022 eruptions, with Hunga Ha’apai intact, but dropping vertically by ~10-15 m. The violence of the 2022 eruption was likely augmented by either caldera collapse or flank collapse from the upper edifice, rapidly unroofing the andesitic magma system and enabling efficient water ingress.

This data provides an essential base layer for assessing changes on the ocean floor, especially to determine any caldera or upper-flank changes. Understanding these changes is crucial for future forecasting future volcanic hazards at Hunga and other nearby large submarine volcanoes.
Airborne emissions of methane at offshore oil platforms in Newfoundland and Labrador, Canada
Authors: Khaleghi Afshan , MacKay Katlyn , Bourlon Evelise , Lavoie Martin , Darlington Andrea , James Lesley A. , Risk David
Published: March 2022

In Canada, offshore oil production facilities are exempt from new methane mitigation requirements that apply to onshore producers. Since onshore oil and gas operations have been shown in Canada to emit more methane than is reported in the federal inventory, it is reasonable to question methane emission levels, and intensity, of Canada’s offshore oil production. In this study, we measured methane emissions from an aircraft equipped with Picarro 2210-i gas analyzer and Aventech wind measurement system (AIMMs_30). The top-down emission rate retrieval algorithm (TERRA) was used to calculate the emission rate using a mass balance technique. The algorithm was developed by Environment and Climate Change Canada and has been used previously for airborne emissions measurement campaigns around oil and gas facilities. In addition to mass balance estimates, we also derived estimates from downwind transects using a Gaussian Dispersion model. We flew around each of the 3 offshore facilities 3 times to ensure accurate measurements considering the unpredictable offshore weather conditions. Our emissions estimates were overall comparable with inventory estimates, which demonstrate a much lower methane emissions intensity than onshore oil production in western Canada. We compared our results against reported values for other aircraft-based measurement studies including those in the North Sea and the Gulf of Mexico. Although average measured emission rates in Eastern Canada are higher in absolute terms than similar platforms in the Gulf of Mexico or the North Sea, methane emission intensity is lower because production levels are very high.

Keyword: Methane emission rate, Inventories, Mass balance, Top-down, Airborne measurement
Swarm in-situ electron density disturbances over Greenland compared to VTEC disturbances from ground-based GNSS, during three geomagnetic storms
Authors: Jarmolowski Wojciech , Monte-Moreno Enric , Wielgosz Paweł , Paziewski Jacek , Hernandez-Pajares Manuel , Miloch Wojciech , Jin Yaqi , Berdermann Jens , Hoque Mainul , Høeg Per , Garcıa Rigo Alberto , Milanowska Beata , Clausen Lasse , Yang Heng , Lyu Haixia , Orús-Pérez Raul
Published: March 2022

The objective of the work is to compare geomagnetic storm impact on the ionosphere parameters measured from ground-based GNSS permanent stations and Swarm satellites. The analyses compare the changes of vertical total electron content (VTEC) measured along the entire ionosphere cross-section to the variations of electron density (ED) on the orbit, at ~500 km altitude. The objective is how sensitive are the measures of electric field variations available on the Earth, with respect to those obtained from the satellite orbit. The study applies Swarm in-situ ED measured by Langmuir Probes (LP), topside TEC from onboard Swarm GNSS receivers and vertical TEC determined from ground-based GNSS stations available in the area of the Northern polar cap. Ground and satellite data were processed in different ways. Ground-based VTEC is available at number of stations providing heterogeneous but useful horizontal coverage. Therefore ROTI values were calculated from VTEC as gradient values capable to indicate the disturbances. These ROTI values were interpolated spatially to obtain maps. Swarm passes over the polar cap starting from 45° lasts for several minutes each, and repeat in this region approximately every 1.5 h. Such along-track collected small data samples are useless in horizontal correlation analysis. Therefore Swarm data disturbances, in this case, are extracted with the use of Fourier transform-based filtering and are also analyzed in the spectrograms based on short-term Fourier transform (STFT). The case study has used three geomagnetic storms, namely: the St. Patrick storm of March 17, 2015, the storm on June 22, 2015, and the storm on August 25-26, 2018. The results reveal differences in storm impact on VTEC measured by GNSS on the Earth, with respect to the storm influence on topside TEC and in-situ ED disturbances measured onboard the Swarm. The overall summary statistics provide some preliminary conclusions on different times of the reaction to the storm. Additionally, some interesting differences between FT filtering and a very popular moving average are shown, with respect to Swarm data. The research was done in the frame of the FORSWAR project (Forecasting Space Weather in the Arctic Region) funded by ESA.
Sedimentary record of tectonic inversion and basin partitioning in the South-Central Pyrenees during the Late Cretaceous.
Authors: Oms Oriol , Dinarès-Turell Jaume , Vicens Enric , Boix Carme , Gil-Gil Javier , García-Hidalgo José , Ramírez-Pérez Pedro
Published: March 2022

The tectosedimentary evolution of the Pyrenees is a well-known example of the interaction among growth strata, sediment routing, sequence stratigraphy and evolving depositional environments. During the Late Cretaceous a general tectonic inversion from rift to foreland basin is recorded. Such evolution is related to the Iberian plate kinematics and is evidenced by the substitution of carbonate systems by mixed and clastic ones, that will persist until Oligocene times.

The precise evolution and timing of the inversion stages is addressed by studying the Noguera Pallaresa river transect (composite Collegats -Font de la Plata section) which is further compared with other areas. This classical transect also permits to study successive structure reactivations after inversion started. Robust magnetostratigraphic results from several stratigraphic units (Font de les Bagasses marls, Riu Boix platform or Montsec sands) permit an accurate dating of the beginning of the inversion stage within the Santonian and also provide time constraints (together with absolute datings) for the rest of the Late Cretaceous. The role of the Montsec thrust as paleohigh controlling basin partitioning is also evidenced by a large paleocurrent database obtained from the Areny sandstone formation. Sedimentological data and carbonate microfacies determinations also provide refinements of the complex interaction between tectonic and climatic factors.

Finally, the combined biomagnetostratigraphic age model is compared with the peripheral areas of the foreland such as Serres Marginals, Eastern and Northern Pyrenees. It is strongly suggested that the formation of accommodation space for sedimentation due to the inversion was fully synchronous all over the orogen.