bluuebunny/crossref_metadata_2025 huggingface dataset:
Tropical Tropospheric Ozone from Sentinel-5P TROPOMI data: Synergy of CCD/CSL retrievals
Authors: Eichmann Kai-Uwe , Weber Mark , Burrows John P.
Published: March 2021

The TROPOspheric Monitoring Instrument (TROPOMI), on board the Sentinel 5 precursor (S5p) satellite, was launched in October 2017. The TROPOMI instrument has high spatial resolution and daily coverage of the Earth. About two years of level 2 data (versions up to 2.1.4) of OFFL GODFIT ozone and OCRA/ROCINN CRB (fraction and height) are available. Using these datasets, we derive tropical tropospheric ozone using the convective CCD cloud differential method for tropical tropospheric column ozone (TTCO) [DU] and the CSL cloud slicing method for upper tropospheric ozone volume mixing ratios (TUTO) [ppbv].

The CCD algorithm was optimized for TROPOMI with respect to the reference sector Above Cloud Column Ozone field (ACCO) by adjusting it in time and latitude space in order to reduce data gaps in the daily ACCO vectors. Daily total ozone gridded data with a latitude/longitude resolution of 0.5°/1° are used to minimize the error from stratospheric ozone changes.

The CSL algorithm (CHOVA: Cloud Height induced Ozone Variation Analysis) was developed to fully exploit the S5p instruments characteristics. The data is spatially sampled to a 2° latitude/longitude grid. A temporal sampling of cloud/ozone data is not necessary anymore due to the high amount of S5p measurements. Comparisons with NASA/GSFC SHADOZ ozone sondes show good agreement (low bias and high dispersion) for both methods taking into account the principal differences between sonde point measurements and satellite sampled mean value. The CHOVA results from the pacific sector are now used as input for the CCD method to adjust the height dependent columns to a fixed pressure level.    

The work on TROPOMI/S5P geophysical products is funded by ESA and national contributions from the Netherlands, Germany, Belgium, and Finland.
Volcanic deformation at Sakurajima between 2015 and 2020 revealed by Sentinel-1 InSAR time series
Authors: Vásquez-Castillo Alejandra , Hort Matthias
Published: March 2021

Surface displacements recorded in volcanically active regions are often driven by magmatic, hydrothermal or tectonic processes. Measuring the deformation experienced by the ground as a result of these processes allows to constrain the changing volcanic conditions and to infer quantitative estimates of the subsurface magmatic storage, thus increasing the knowledge of volcanic hazards for the closest local population. Interferometric synthetic aperture radar (InSAR) has proven to be an useful tool to observe ground deformation in volcanically active areas like the Sakurajima volcano, southern Japan, one of the most active volcanoes worldwide. Its current activity is characterized by degassing and almost daily explosive eruptions. We performed an InSAR time series analysis to identify and characterize time-dependent ground deformation using Sentinel-1 data between 2015 and 2020. During this period several large explosions with plume heights of up to 6000 m occurred. We found evidence of ground deformation associated with precursory inflation connected to major explosions. In addition, we processed interferograms spanning a remarkable event that occurred on August 15 2015, in which we identified strong deformation around the Showa crater, in agreement with previous studies.
Investigating the controls of submarine landslides and associated hazards in Pangnirtung Fiord, Eastern Baffin Island (Nunavut)
Authors: Sedore Philip , Normandeau Alexandre , Maselli Vittorio
Published: March 2021

High-latitude fiords are susceptible to hazardous subaerial and submarine slope failures. Recent investigations have shown that past slope failures in fiords of Greenland and Alaska have generated devastating landslide induced tsunamis. Since coastal communities inhabit these high-latitude fiords, it is critical to understand the slope failure recurrence time, their distribution, potential triggers, and ability to generate tsunamis. In this study, we identified > 50 near-surface submarine landslides in Pangnirtung Fiord, eastern Baffin Island, Nunavut, using multibeam bathymetric and sub-bottom profiler data, along with sediment gravity-cores collected in 2019. Morphometric and morphological analyses, along with sedimentological analyses, were carried out on submarine landslide deposits to quantify their spatial and temporal distribution throughout the fiord and to evaluate the factors that may have triggered the slope failures.

Combining bathymetric with topographic data from unmanned aerial vehicle imagery, we found that most of these landslide deposits are relatively small (~ 0.08 km2) and are associated with outwash fans and steep fiord sidewalls. However, since most slope failure head scarps lie between the intertidal zone and ~30 m water depth, they could not be mapped, which makes it challenging to determine the triggers of the submarine slope failures. Radiocarbon dating reveals that most of these surficial landslide deposits are younger than 500 years old and that they were most likely triggered at different times. This finding highlights a high recurrence rate of slope failures within the fiord, suggesting that localised triggers are responsible for slope failures within the fiord, as opposed to widespread, seismically induced triggers which do not occur as frequently in the study area. In addition, the elongated morphology of the landslide deposits and the varying degrees of landslide deposit surface roughness supports localised point-source triggers. Since most landslides are associated with subaerial outwash fans and deltas, we suggest that triggers of these relatively frequent submarine landslides within Pangnirtung Fiord include rapid floodwater input, subaerial debris flows, and sea-ice loading during low tide.

This research shows that slope failures in a high-latitude fiord are affected by the interaction of numerous subaerial and submarine processes, leading us to speculate that a potential increase in the frequency of subaerial debris flows and river floods due to climate change may increase the recurrence of submarine landslides.
The role of sea ice for plastic pollution in the Arctic
Authors: Peeken Ilka , Bergami Elisa , Corsi Ilaria , Hufnagl Benedikt , Katlein Christian , Krumpen Thomas , Löder Martin , Wang Qiuang , Wekerle Claudia
Published: March 2021

Marine plastic pollution is a growing worldwide environmental concern as recent reports indicate that increasing quantities of litter disperse into secluded environments, including Polar Regions. Plastic degrades into smaller fragments under the influence of sunlight, temperature changes, mechanic abrasion and wave action resulting in small particles < 5mm called microplastics (MP). Sea ice cores, collected in the Arctic Ocean have so far revealed extremely high concentrations of very small microplastic particles, which might be transferred in the ecosystem with so far unknown consequences for the ice dependant marine food chain.  Sea ice has long been recognised as a transport vehicle for any contaminates entering the Arctic Ocean from various long range and local sources. The Fram Strait is hereby both, a major inflow gateway of warm Atlantic water, with any anthropogenic imprints and the major outflow region of sea ice originating from the Siberian shelves and carried via the Transpolar Drift. The studied sea ice revealed a unique footprint of microplastic pollution, which were related to different water masses and indicating different source regions. Climate change in the Arctic include loss of sea ice, therefore, large fractions of the embedded plastic particles might be released and have an impact on living systems. By combining modeling of sea ice origin and growth, MP particle trajectories in the water column as well as MPs long-range transport via particle tracking and transport models we get first insights  about the sources and pathways of MP in the Arctic Ocean and beyond and how this might affect the Arctic ecosystem.
Event-driven dynamics of the total mobile inventory in soils - Results from a comparative multi-year lysimeter study
Authors: Lehmann Katharina , Lehmann Robert , Totsche Kai U.
Published: March 2021

A diverse size- and matter spectrum of inorganic, organo-mineral and organic substances, and dissolved, colloidal, but also larger particulate matter, including microbiota, is mobile in soil and potentially involved in matter interchange between surface and subsurface ecosystems. Specifically including the widely neglected particulate fractions, conditions and field-scale factors controlling the long-term seasonal and episodic dynamics of the “total mobile inventory” (Lehmann et al., 2021), in undisturbed soil and its translocation through the subsurface of the Critical Zone is almost unknown. To overcome this knowledge gap, we established long-term soil monitoring plots in the Hainich Critical Zone Exploratory (HCZE; NW-Thuringia, central Germany). Soil seepage from 22 tension-controlled lysimeters in topsoil and subsoil, covering different land use (forest, pasture, cropland) in the topographic recharge area of the HCZE, was collected and analyzed by a variety of analytical methods (physico-/chemical and spectroscopic) on a regular (biweekly) and event-scale cycle. Atmospheric forcing was found to be the major factor triggering the translocation of the mobile inventory, mainly causing considerable seasonality in the solute signature (e.g., sulphate) and seepage pH. However, episodic high-flow (infiltration) events rather than seasonality caused mobilization of significant amounts of particulates, for instance, after snow melts or rainstorms. Noteworthy, particulate organic carbon translocated during the winter-season infiltration events, accounted for up to 80% of annual fluxes. On average, 21% of the total OC of the seepage was particulate (>0.45 µm). Our study provides field-scale evidence for the importance of the mobile inventory fraction >0.45 µm for soil elemental dynamics and budgets. We, thus, suggest involving suspended fractions in environmental monitoring programs, although requiring adapted sampling procedures.

 

References:

Lehmann, K., Lehmann, R., & Totsche, K. U. (2021). Event-driven dynamics of the total mobile inventory in undisturbed soil account for significant fluxes of particulate organic carbon. Science of The Total Environment, 143774.
Source physics interpretation of non-self-similar double-corner frequency source spectral model JA19_2S
Authors: Ji Chen , Archuleta Ralph
Published: March 2021

Source spectral models developed for strong ground motion simulations are phenomenological models that represent the average effect that the source processes have on near fault ground motion. Their parameters are directly regressed from the observations and often do not have clear meaning for the physics of the source process. We investigate the relation between the kinematic double-corner frequency (DCF) source spectral model JA19_2S (Ji and Archuleta, BSSA, 2020) and static fault geometry scaling relations proposed by Leonard (2010). We derive scaling relations for the low and high corner frequency in terms of static stress drop, dynamic stress drop, fault rupture velocity, fault aspect ratio, and relative hypocenter location. We find that the non-self-similar low corner frequency  scaling relation of JA19_2S model for 5.3<M<6.9 earthquakes is well explained using the fault length scaling relation of Leonard’s model combined with a constant rupture velocity. Earthquakes following both models have constant average static stress drop and constant average dynamic stress drop. The high frequency source radiation is controlled by seismic moment, static stress drop and dynamic stress drop but strongly modulated by the fault aspect ratio and the hypocenter’s relative location. The mean, scaled energy  (or apparent stress) decreases with magnitude due to the magnitude dependence of the fault aspect ratio. Based on these two models, the commonly quoted average rupture velocity of 70-80% of shear wave speed implies predominantly unilateral rupture.
Harmonic fluctuations in the relative paleointensity data?
Authors: Ernesto Marcia , Britto Thamyris , Caminha-Maciel George
Published: March 2021

The existing relative paleointensity (RPI) database allowed the construction of reliable stacking curves for at least the last 1 Myr. Observed fluctuations in the RPI curves suggest both lithologic/climatic influence or geodynamo processes. Stacked power spectra for RPI data from ten North and South Atlantic cores revealed a spectral peak at ~5.3kyr for data covering the last 100 kyr. This signal exhibits a similar phase for most of the series. The observed spectral peak has no apparent correspondence in the benthic O18 spectra from the same cores, suggesting the RPI signal is free from the climatic influence. Therefore, it may be a real geodynamo feature.
Landscape and hazard evolution during the Montserrat volcanic crisis 1995–2010: an integrated simulation with r.avaflow
Authors: Mergili Martin , Pudasaini Shiva P.
Published: March 2021

An active phase of Soufrière Hills Volcano (Montserrat, Lesser Antilles) has started in 1995 and had its most intense period between 1995 and 2010, when phases of lava dome growth were interrupted by dome collapses triggering ash clouds and different types of pyroclastic flows. These flows were released in various directions, so that two thirds of the island were left in an inhabitable state. The material deposited was later remobilized through lahar flows, burying the centre of the former capital town of Plymouth. In the present work, we attempt to back-calculate the sequences of dome growth – pyroclastic flows, and the subsequent lahar flows, in an integrated way, using the mass flow simulation tool r.avaflow. Thereby, we build on the reconstruction of the pre-event topography as well as on various reference data obtained from the large amount of available literature – mainly, the peak elevation and volumes of the lava domes, the impact areas of the flow processes, and ash fall characteristics. Most observations are successfully reproduced with physically plausible, though calibrated, parameter sets and temporal scaling of lava dome growth. Due to the complexity and multi-stage nature of the volcanic crisis, a number of simplifications had to be introduced, such as considering only the twelve largest sequences of dome growth and pyroclastic flows, and evaluating some of the results on the basis of aggregated impact areas for more than one event. Consequently, the results reflect a strong conceptual component, but can - at least in part - be considered useful for predictive modelling of similar events. Another scope of the simulation results, however, is its educational use. Appropriately presented, they greatly facilitate the generation of a better understanding for complex chains of volcanic processes and their consequences to learners at various levels in different educational contexts, from school and university all the way to targeted awareness-building campaigns.
ML5.5 and ML6.2 earthquakes in central Croatia during COVID-19 pandemics
Authors: Dasović Iva , Herak Marijan
Published: March 2021

In 2020, central part of Croatia was struck by two major earthquakes: on 22 March in Zagreb and on 29 December near Petrinja. Both earthquakes happened while country was in COVID-19 „lockdown“.

Magnitude ML5.5 earthquake occurred on Sunday morning at 5:24 UTC (6:24 CET) with the epicentre at Medvednica Mt., in the Zagreb's outskirts, just 7 km to the north of the centre of the Croatian capital. The intensity in the epicentre and in the historic centre was estimated as VII EMS, and a young girl lost her life. The earthquake struck just a day after public transport was suspended for 30 days, three days after public gatherings of more than five people were forbidden, the restaurants, shops (except for groceries, hygienic and other necessary items) and cultural institutions were closed, and six days after closure of schools and universities. A day after the main event, people were forbidden to leave their city/town/municipality of residence without written permission of local government. At that time, Croatian “lockdown” was described as one of the strictest ones in EU.

On Tuesday 29 December 2020 at 11:19 UTC (12:19 CET) a magnitude ML6.2 (MW6.4) earthquake occurred in rural area of central Croatia, near town of Petrinja. It was preceeded by magnitude ML5.0 and ML4.7 events a day before. These events caused significant damage to buildings in Petrinja and Glina and the surrounding villages. The highest intensity was estimated as VIII–IX EMS and seven people lost their lives. This sequence happened also during the “lockdown” due to COVID-19 pandemics with strict measures imposed on 21 December 2020, some of which were cancelled after the mainshock.

We will discuss events and processes that followed these strong earthquakes and how having to deal with two damaging events only nine months apart and in the unusual pandemic-related circumstances affected our work as seismologists but also our “everyday” lives.
Rock mass damaging investigation through the analysis of microseismic monitoring data collected on rock masses
Authors: D'Angiò Danilo , Lenti Luca , Martino Salvatore
Published: March 2021

Rock mass damaging investigation is a main research topic in the ambit of rock fall hazard assessment. Roads and railways interruptions, as well as damages of buildings, are among the main inconveniences due to the detachment of unstable sectors of highly jointed rock masses. The contribution of rock mass creep together with natural and anthropic forcings leads to the accumulation of inelastic strain within the rock mass and to the formation of new joints or to the extension and movement of the pre-existing ones. The associated stress release produces tiny vibratory signals (known as microseismic emissions) that can be detected by on-site installed microseismic monitoring networks. Monthly and annual microseismic monitoring data can provide information on seismicity increase over certain periods and on the deterioration of rock properties as the elastic moduli. However, other seismic attributes may support the comprehension of rock mass damaging processes. In particular, the analysis over time of the damping ratio associated with the microseismic emissions could indicate transient and permanent changes within the micro-joint network. This analysis approach has been already conducted on a three-month long microseismic dataset collected at the Acuto field-lab, which is hosted in an abandoned quarry and is mainly exposed to environmental forcings (rainfalls and thermal cycles); moreover, to account also for anthropic vibrations, preliminary studies were carried out on a rock mass located in proximity of a railway. As a further perspective, the investigation of multi-year seismic dataset acquired on unstable rock masses will allow to better inspect the reliability of this analysis approach for rock mass damaging assessment.
Planetary (Rossby), Inertia-Gravity (Poincaré) and Kelvin waves on the f-plane and β-plane in the presence of a uniform zonal flow
Authors: De-Leon Yair , Garfinkel Chaim I. , Paldor Nathan
Published: March 2021

A linear wave theory of the Rotating Shallow Water Equations (RSWE) is developed in a channel on either the mid-latitude f-plane/β-plane or on the equatorial β-plane in the presence of a uniform mean zonal flow that is balanced geostrophically by a meridional gradient of the fluid surface height. We show that this surface height gradient is a potential vorticity (PV) source that generates Rossby waves even on the f-plane similar to the generation of these waves by PV sources such as the β–effect, shear of the mean flow and bottom topography. Numerical solutions of the RSWE show that the resulting planetary (Rossby), Inertia-Gravity (Poincaré) and Kelvin-like waves differ from their counterparts without mean flow in both their phase speeds and meridional structures. Doppler shifting of the “no mean-flow” phase speeds does not account for the difference in phase speeds, and the meridional structure does not often oscillate across the channel but is trapped near one the channel's boundaries in mid latitudes or behaves as Hermite function in the case of an equatorial channel. The phase speed of Kelvin-like waves is modified by the presence of a mean flow compared to the classical gravity wave speed but their meridional velocity does not vanish. The gaps between the dispersion curves of adjacent Poincaré modes are not uniform but change with the zonal wavenumber, and the convexity of the dispersion curves also changes with the zonal wavenumber. In some cases, the Kelvin-like dispersion curve crosses those of Poincaré modes, but it is not an evidence for the existence of instability since the Kelvin waves are not part of the solutions of an eigenvalue problem. 
Evaluating the age-depth models based on coupled 14C and 210Pb data
Authors: Piotrowska Natalia , Sikorski Jarosław
Published: March 2021

14C and 210Pb methods are regularly used to determine ages and accumulation rates of peat, fen and lake sediments. The overall aim is to estimate the age of discrete layers, which were analysed for environmental proxies. Ideally, the age-depth models should fit the investigated proxy in terms of resolution and give precise results. Nevertheless, the differences in the nature of dating methods and statistical treatment of data need to be considered.

Both 14C and 210Pb signals are integrated over a considerable period. Moreover, they originate from different sources. 210Pb is bound to aerosols and trapped by peat while 14C is bound from atmospheric CO2 by photosynthesis. Hence, 210Pb gives the time span during which the aerosol has been buried, whereas the 14C date gives the time of death of a plant.

After the analysis, the results are usually combined into an age-depth model. This process involves statistical treatment of data during which specific assumptions and simplifications are made. Depending on the algorithm, they lead to alterations in modelled ages compared to unmodelled data. Principally it is a desired result–increasing the robustness and decreasing the uncertainty of the age-depth model. In worse cases models alter the modelled ages to an unacceptable extent, which may be overlooked if the results are treated automatically.

We test the performance of various age-depth modelling algorithms (OxCal P_Sequence, Bacon, clam, MOD-AGE) on a selected true dataset where 14C and 210Pb data overlap and are used simultaneously. Afterwards, a point estimate is selected and used for proxy analysis on a time scale and for calculation of the accumulation rates. We also check the influence of 210Pb calculation method (CRS, ModAge, extrapolation technique) on derived age-depth models.

Together with the thickness of analysed samples the age model provides an information about the time resolution of proxy analysis. While the age-depth curves, except outstanding circumstances, give relatively similar answers within 95% uncertainty ranges, the differences are observed in point estimates and accumulation rate, and they may be relevant for the palaeoenvironmental studies. With this exercise we attempt to assess the uncertainty beyond simple age errors reported from the measurements and age-depth modelling.
Heat flux and the North East Greenland Ice Stream
Authors: Bons Paul D. , de Riese Tamara , Franke Steven , Llorens Maria-Gema , Sachau Till , Stoll Nicolas , Weikusat Ilka , Zhang Yu
Published: March 2021

The prominent North East Greenland Ice Stream (NEGIS) is an exceptionally large ice stream in the Greenland Ice sheet. It is over 500 km long, originates almost at the central ice divide, and contributes significantly to overall ice drainage from the Greenland Ice sheet. Surface velocities in the inland part of the ice stream are several times higher inside NEGIS than in the adjacent ice sheet. Modelling NEGIS is still a challenge as it remains unclear what actually causes and controls the ice stream.

An elevated geothermal heat flux is one of the factors that are being considered to trigger or drive the fast flow inside NEGIS. Unfortunately, the geothermal heat flux below NEGIS and its upstream area is poorly constrained and estimates vary from close to the global average for continental crust (ca. 60 mW/m2) to values as high as almost 1000 mW/m2. The latter would cause about 10 cm/yr of melting at the base of the ice sheet.

We present a brief survey of global geothermal heat flux data, especially from known hotspots, such as Iceland and Yellowstone. Heat fluxes in these areas that are known to be among the hottest on Earth rarely, if ever, exceed 300 mW/m2. A plume hotspot or its trail can therefore not cause heat fluxes at the high end of the suggested range. Other potential factors, such as hydrothermal fluid flow and radiogenic heat, also cannot raise the heat flux significantly. We conclude that the heat flux at NEGIS is very unlikely to exceed 100-150 mW/m2, and future modelling studies on NEGIS should thus be mindful of implementing realistic geothermal heat flux values. If NEGIS is not the result of an exceptionally high heat flux, we are left with the exciting challenge to find the true trigger of this fascinating structure.
Combination of ground-based and space-based GNSS tomography (2021-2025)
Authors: Rohm Witold , Hordyniec Paweł , Möller Gregor , Kryza Maciej , Trzcina Estera , Taszarek Mateusz
Published: March 2021

Global Navigation Satellite Systems (GNSS) sense the atmosphere remotely and provide low-cost, high-quality information about its state. Nowadays, radio occultation (RO) profiles from space platforms and tropospheric delays from ground-based stations are routinely assimilated in Numerical Weather Models  (NWM).

In spite of provision of valuable information for weather forecasting, both space- and ground-based data have significant limitations. The RO technique has low horizontal resolution and does not provide reliable profiles in the first 3-5km of the troposphere. Whereas, the station-specific integrated value of troposphere are sparse and pose a problem to NWM adjoint operator for correcting model fields at different heights. These deficiencies could be resolved by the GNSS tomography technique that utilizes an inverse Radon transform to derive the 3D refractivity distribution over certain troposphere space. The combination of space-based and ground-based observations in the tomographic model will enable us to increase the number of intersections of GNSS signals and improve the refractivity solution within individual model locations. 

The aim of this research is to harness the full potential of Space 4.0 era, rapidly growing numbers of RO and GNSS satellite constellations as well as low-cost GNSS ground-based networks worldwide. We will not only use current infrastructure but also examine impact of future constellations on model performance. 3D model of refractivity from dense observations should be an excellent tool in weather prediction. Our previous research proves that the assimilation of the GNSS tomography outputs into the NWM improves relative humidity and the short-term weather forecasts. Therefore, the research goal of this project is to assess the benefit of integrated tomography model on the severe weather prediction and urban scale weather models.
Spring freshet on East European plain: changes in drivers and conditions during last three decades
Authors: Kharlamov Maxim , Kireeva Maria , Varentsova Natalia
Published: March 2021

Over the past 20 years, the climate on the East European plain tends to be significantly warmer and drier. Winters became shorter and spring freshet’s conditions have been changed significantly. Maximum snow depth was the most important factor of spring freshet formation 30 years ago, but nowadays it has no significance at all and main factor today is melt water losses on infiltration and evaporation.

We registered a decrease in the period of stable snow accumulation (on average by 20% in the southern and southwestern parts of the East European Plain) because of the increase in winter temperatures. More often during first part of winter snow cover disappeared totally. The number of thaws and their duration at the end of the winter also increase and this leads to earlier and more prolonged melting of the snow pack. In these conditions, an extremely low spring freshet is formed. Our studies show that with the condition of an equal maximum snow depth the slow snowmelt forms the spring freshet up to 4 times less in volume than the fast melting.

Soil moisture also plays an important role in the melt water losses. The most part of the East European Plain is characterized by a decrease in soil moisture in late autumn, which indicates increased losses during snow melting period.

Still, the most significant changes in the structure of the factors of spring freshet formation are common to the southern and southwestern parts of the East European Plain. In the northern part, conservative factors still dominate, although this area is characterized by the significant increase in winter temperatures.

The study was supported by Russian Science Foundation Proj. №19-77-10032
Evaluating RCM Added Value in Climate Change Projections
Authors: Scinocca John
Published: March 2021

When a regional climate model is used to investigate and understand an issue related to climate change, in principle, an understanding of that issue will already be available from the global GCM simulations that provided the RCM driving data. From this perspective, the downscaling exercise is essentially one of adding understanding, or value, to an existing GCM result and so, it would seem sensible that statements regarding the value added by RCM downscaling be put into the context of the driving GCM's results. While such added value is central to the downscaling exercise, its evaluation is an intrinsically difficult undertaking for a variety of reasons - not least of which is the lack of a consensus on how added value should be defined. Irrespective of the definition of added value, however, progress can still be made on this issue. In the present study, we develop a methodology for an appreciable difference analysis of the climate change results in RCMs relative to their driving GCMs.  Since added value can only exist where appreciable differences occur in the climate change results of the global and regional models, the present approach provides a useful tool to direct attention to areas where added value potentially exist and conversely rule out areas where it does not.  The approach is illustrated on an ensemble of CMIP5 climate change experiments using the Canadian Earth-system model CanESM2 and its downscaled counterpart CanRCM4.
Geochemistry of gas emissions in the volcano-tectonic environment of the Eastern Carpathians
Authors: Kis Boglarka-Mercedesz , Palcsu Laszlo , Zsigmond Andreea-Rebeka , Tamas Dan Mircea , Szollosi Istvan , Szalay Roland , Harangi Szabolcs
Published: March 2021

The Eastern Carpathians are characterized by intense gas emissions starting from the Neogene to Quaternary volcanic structures, especially the youngest dormant volcano, Ciomadul, but occurring also far away from these, in the Cretaceous flysch units. This is the most intensive degassing area from Romania. The gas emissions appear in different forms: dry gas, named mofettes and bubbling gas when they are accompanied by groundwater. The major components of these gas emissions are: CO2, CH4, N2 and sometimes H2S. Recent studies reveal a magmatic contribution up to 60% in these emissions (Vaselli et al., 2002, Kis et al., 2019). Gases are also present dissolved in groundwater and transported to the surface by CO2-rich springs. Besides these visible emissions, the gases come to the surface as diffuse degassing from the soil. We started a systematic geochemical investigation of the gas emissions in the volcano-tectonic environment of the southern part of the Eastern Carpathians, together with a 5-year monitoring of the gas emissions. Our primary aims are to constrain the flux of CO2, the origin of the different gas species, their interaction, and their relationship with the geodynamic background. Our findings could be integrated to the global carbon estimations, currently missing from the worldwide evaluations and could help the establishment of a long-term monitoring system of the gases in the area.

This work was supported by a grant of the Romanian Ministry of Education and Research, CNCS - UEFISCDI, project number PN-III-P1-1.1-TE-2019-1908, within PNCDI III and the project GTC 32144 supported by Babes-Bolyai University, Romania.
Multi-year statistical analysis of properties of current sheets at 1 AU
Authors: Khabarova Olga , Sagitov Timothy , Kislov Roman , Li Gang
Published: March 2021

We use the multi-year open acees database of current sheets identified at 1 AU with the one-second resolution from ACE data (https://csdb.izmiran.ru ) to study properties of current sheets in the solar wind. We find that the CS daily rate (the number of CSs per day) R correlates with the solar wind temperature T rather than with the solar wind speed V and is proportional to the sum of the kinetic and thermal energy density. The main statistical results preliminary obtained in the study are as follows:

There is clustering of CSs.

Maxima of R are associated with stream/corotating interaction regions (SIRs/CIRs) and interplanetary mass ejection (ICME) sheaths.

On average, one-three thousands of CSs are detected daily at the Earth’s orbit. The best-fit parameter is (V 2 (N+5 N ' ) + 10( N+ N ' )T )/5000 if V is given in km/s, T - in K, N is given in cm-3,  and N ' =2 cm-3 is the background level of the solar wind density. The correlation coefficient between the parameter and R  is ~0.8.

There is no obvious connection between the daily CS rate and the solar cycle. However, this preliminary conclusion should be reconsidered after the expansion of the CS database to several solar cycles.

O.K. and R.K. are supported by Russian Science Foundation grant No. 20-42-04418. T.S. acknowledges the HSE’s general support and encouragement of student’s scientific activity.
A chemical composition map for Titan’s surface
Authors: Solomonidou Anezina , Coustenis Athena , Lopes Rosaly , Malaska Michael , Le Gall Alice , Schmitt Bernard , Schoenfeld Ashley , Wall Steve , Lawrence Kenneth , Sotin Christophe , Matsoukas Christos , Markonis Yannis , Drossart Pierre , Elachi Charles
Published: March 2021

The investigation of Titan’s surface chemical composition is of great importance for the understanding of the atmosphere-surface-interior system of the moon. The Cassini cameras and especially the Visual and infrared Mapping Spectrometer has provided a sequence of spectra showing the diversity of Titan’s surface spectrum from flybys performed during the 13 years of Cassini’s operation. In the 0.8-5.2 μm range, this spectro-imaging data showed that the surface consists of a multivariable geological terrain hosting complex geological processes. The data from the seven narrow methane spectral “windows” centered at 0.93, 1.08, 1.27, 1.59, 2.03, 2.8 and 5 μm provide some information on the lower atmospheric context and the surface parameters. Nevertheless, atmospheric scattering and absorption need to be clearly evaluated before we can extract the surface properties. In various studies (Solomonidou et al., 2014; 2016; 2018; 2019; 2020a, 2020b; Lopes et al., 2016; Malaska et al., 2016; 2020), we used radiative transfer modeling in order to evaluate the atmospheric scattering and absorption and securely extract the surface albedo of multiple Titan areas including the major geomorphological units. We also investigated the morphological and microwave characteristics of these features using Cassini RADAR data in their SAR and radiometry mode. Here, we present a global map for Titan’s surface showing the chemical composition constraints for the various units. The results show that Titan’s surface composition, at the depths detected by VIMS, has significant latitudinal dependence, with its equator being dominated by organic materials from the atmosphere and a very dark unknown material, while higher latitudes contain more water ice. The albedo differences and similarities among the various geomorphological units give insights on the geological processes affecting Titan’s surface and, by implication, its interior. We discuss our results in terms of origin and evolution theories.

[1] Solomonidou, A., et al. (2014), J. Geophys. Res. Planets, 119, 1729; [2] Solomonidou, A., et al. (2016), Icarus, 270, 85; [3] Solomonidou, A., et al. (2018), J. Geophys. Res. Planets, 123, 489; [4] Solomonidou, A., et al. (2020a), Icarus, 344, 113338; [5] Solomonidou, A., et al. (2020b), A&A 641, A16; [6] Lopes, R., et al. (2016) Icarus, 270, 162; [7] Malaska, M., et al. (2016), Icarus 270, 130; [8] Malaska, M., et al. (2020), Icarus, 344, 113764.
Solar wind speed and rotational shear at coronal hole boundaries, impacts on magnetic field inversions
Authors: Pinto Rui , Poirier Nicolas , Kouloumvakos Athanasis , Rouillard Alexis , Griton Léa , Fargette Naïs , Kieokaew Rungployphan , Lavraud Benoît , Brun Allan Sacha
Published: March 2021

The solar wind is frequently perturbed by transient structures such as magnetic folds, jets, waves and flux-ropes that propagate rapidly away from the Sun over a large range of heliocentric distances. Parker Solar Probe has revealed that rotations of the magnetic field vector occur repeatedly at small heliocentric distances, on regions that also display surprisingly large solar wind rotation rates. Sun-to-spacecraft connectivity analysis shows that a large fraction of the solar wind flows probed so far by Parker Solar Probe were formed and accelerated in the vicinity of coronal hole boundaries.
We show by means of of global MHD simulations that coronal rotation is highly structured in proximity to those boundary regions (in agreement with preceding SoHO/UVCS observations), and that enhanced poloidal and toroidal flow shear and magnetic field gradients also develop there. We identified regions of the solar corona for which solar wind speed and rotational shear are significant, that can be associated with field-aligned and/or transverse vorticity, and that can be favourable to the development of magnetic deflections. Some of these wind flow shears are driven through large radial extensions, being noticeable tens of solar radii away from the surface, and therefore have a potential impact on the propagation of such magnetic perturbations across extended heights in the solar wind. We conclude that these regions of persistent shears are undoubtedly sources of complex solar wind structures, and suggest that they can trigger instabilities capable of creating magnetic field reversals detected in-situ in the heliosphere.
Our simulations furthermore indicate that the spatial structure of the solar wind shear will become more complex as the solar cycle progresses, with strong and extended shears appearing at heliographic latitudes that will be probed by Solar Orbiter in the near future.
NOx emissions from U.S. oil and gas production using TROPOMI NO2 and the divergence method
Authors: Dix Barbara , Francoeur Colby , McDonald Brian , Serrano Raquel , Veefkind Pepijn , Levelt Pieternel , de Gouw Joost
Published: March 2021

The development of horizontal drilling and hydraulic fracturing has led to a steep increase in the U.S. production of natural gas and crude oil from shale formations since the mid 2000s. Associated with this industrial activity are emissions of ground-level ozone precursors such as nitrogen oxides (NOx). Satellite data are important in this context, because surface measurements are limited or non-existent in rural regions, where most U.S. oil and gas production operations take place. Here we use TROPOMI NO2 observations to study NOx emissions coming from oil and natural gas production sites. Applying the divergence method we quantify basin wide emissions from well pad fields and aim to push spatial and temporal resolution of this technique. The divergence was method introduced by Beirle et al. (Science Advances 2019) to quantify point source emissions. It relies on calculating the divergence of the NO2 flux to derive NOx sources and estimating the NO2 lifetime to quantify sinks. Our analysis will include an assessment of different methods to constrain the NO2 lifetime, which becomes particularly important when applying this method to larger areas. Further we will compare our results with bottom-up derived emissions. Here we use the Fuel-based Oil & Gas (FOG) inventory that calculates NOx emissions based on fuel consumption. Initial results show good agreement for the Permian Basin (NM, TX) and we will expand our analysis to other U.S. basins.
Where do the good foragers live?
Authors: Weiser Martin , Koubek Tomáš , Herben Tomáš
Published: March 2021

Plant species differ in their ability to preferentially grow their roots into nutrient-rich patches in the substrate - this aspect of plant phenotypic plasticity is known as "root foraging". Using a set of approx. 80 Central European herbaceous species of open habitats we show how the root foraging precision of the species is linked to their usual environment. We have obtained the root foraging data experimentally and we combine them with tabelar data that describe species' preference for soil moisture and soil nutrients availability (Ellenberg's Indicator Values), species' ability to occupy frequently disturbed habitats and typical habitats of the species in general. 
Implication of Mesoproterozoic (∼1.4 Ga) magmatism within Sette-Daban (Southeast Siberia)
Authors: Malyshev Sergey , Khudoley Andrey , Ivanov Alexei , Kamenetsky Vadim , Kamenetsky Maya
Published: March 2021

Numerous Mesoproterozoic mafic dyke swarms are known in Siberia. The main intrusions are concentrated in the northern part of the platform and in Sette-Daban (southeastern part of Siberia), and single intrusions are known on all the outcrops of the crystalline basement in the southern part. The largest dyke swarms are located on the Anabar shield and Sette-Daban (with ~1500 Ma and 1000-950 Ma, respectively [1,2]). In the period 1400-1300 Ma, single intrusions are known: 1382 ± 2 Ma [3] on the Anabar shield, 1385 ± 30 Ma [4] on the Udzha uplift, Listvyanka and Goloustnaya dykes in the south of the platform –  1350 ± 6 Ma [5] and 1338 ± 3 Ma [6], respectively. Also, there is the north-trending dolerite dyke at Sette-Daban, which cuts the Lower Riphean sediments of the Uchur Group. The age of this dike was estimated as 1339 ± 59 Ma employing Sm-Nd isochrone [7]. We report here a new U-Pb age on apatite, Nd isotopy, and geochemistry for this dolerite dyke.

A typical apatite grain used for the U-Pb dating. On the  Tera-Wasserburg diagram, the regression line intercepts in the lower part the concordia line at 1419 ± 15 Ma. The chemical composition of this dyke corresponds to subalkaline basalts (SiO2 = 45.6, Na2O+K2O = 3.9 wt%). The rocks correspond (Mg# = 61) to the calc-alkaline series (FeO*/MgO = 1.1) with a low content of TiО2 (1.25 wt %). A clear negative Nb-Ta anomaly on the multielement diagram suggests an IAB affinity. Incompatible element ratios such as Th/Yb, Nb/Th, Nb/Yb, Zr/Nb also suggest that these dolerites are close to arc-related basalts in composition. Eps(Nd) calculated to the initial value at 1400 Ma shows a slightly negative value -0.2, which is considered as mantle source with contribution from the enriched source.

Geochemical and Nd isotopy characteristics show the affinity of the Sette-Daban dyke with low-Ti series of the Phanerozoic flood basalt provinces (e.g. Karoo, Siberian traps, etc. [8,9]) with the suggestion that these dolerites were generated from a metasomatized subcontinental lithospheric mantle source. Assuming geochemical characteristics and new U-Pb age of the dolerite we propose flood basalt province in the southeast Siberia in Mezoproterozoic (~1400 Ma).

The research was supported by the Russian Science Foundation grant (19-77-10048).

 
Results of ground and UAV based EM investigations at the gold promising area (Altay Republic, Russia)
Authors: Antashchuk Kseniia , Atakov Alexey , Kocherov Anton
Published: March 2021

The results of different scale EM investigations at the gold prospective area in the Altay republic are considered. The study was aimed at the first one to detect the prospective area of gold-deposits location and also to test the UAV based EM system. At the first stage the AMT surveys along 20 km length line were implemented. Their results and geological information allowed us to delineated the small area with size about 2x4 km for detailed survey. The ERT, IP, magnetometry and ground and UAV based EM surveys were implemented. EM surveys were carried out using VLF field and CS. The horizontal electric dipole of 1.6 km in length was used as a source of EM field and it produced the signals of rectangular wave form at 500 Hz. Three magnetic components of EM field (Hx, Hy, Hz) were measured with sampling frequency 312 kHz. Data were obtained in the range 500 Hz – 100 kHz. There are the few VLF stations in the studied area and the general information were obtained from the measurements using CS technique. The comparison of ground-based EM soundings results with ERT data shows good correlation. In addition, the UAV based measurements possibility were shown and their results allow to map the general features of the area geological structure. The mineralized fault zones characterized by high conductivity and IP anomaly were delineated and they are the most promising for gold-deposits detection.
The 3D Structure of Atmospheric Blocking: Role of Moisture and Response to Climate Change
Authors: Nabizadeh Ebrahim , Lubis Sandro , Hassanzadeh Pedram
Published: March 2021

Atmospheric blocking is a large-scale weather phenomenon that interrupts the prevailing eastward progression of pressure systems and can result in weather extremes in the midlatitudes. Due to their devastating consequences, understanding the changes of blocking in response to climate change has been of great interest in recent years. In this study, we investigate the 3D structure of blocking events in reanalysis and two large-ensemble, fully coupled GCM simulations: NCAR’s CESM1 Large-Ensemble Project (LENS) and GFDL-CM3 large-ensemble project. Here we compare the climatology of blocks in the models with reanalysis and show that the structure of the blocks is remarkably reproduced well in the GCMs, given that these models are known to have biases in reproducing the climatological Northern Hemisphere large-scale circulation. The results of our composite analysis indicate that the blocks exhibit an equivalent-barotropic structure in both summer and winter seasons over both oceans and continents in the northern hemisphere. However, blocking events are stronger in winters compared to summers. We also notice a significant latent heating associated with ascending airstream on the east side of blocks. This warming, which is stronger in winter especially over the ocean basins, leads to a westward shift in the temperature anomaly during blocking episodes. Furthermore, we study the response of the blocks to climate change (RCP8.5) and find that blocking events will be weakened in the summer of three different northern hemisphere regions. However, wintertime blocks’ responses to climate change are more complex than those in summers and depend on the regions and atmospheric pressure levels. Finally, we examined the response of surface temperature associated with blocking events. We have found that the surface temperature response associated with blocking events will be weaker over all the regions in the winter season. However, during summer, the temperature responses will be slightly stronger over Russia and partially over the two ocean basins. Our results suggest that summertime blocking events over Russia are going to be more impactful compared to those over the ocean basins.