bluuebunny/crossref_metadata_2025 huggingface dataset:
Validation of swath processed Cryosat-2 SARin data with different validation datasets at four different locations.
Authors: Havelund Natalia , Sørensen Louise , Simonsen Sebastian
Published: March 2021

Monitoring the Ice Sheets and ice caps in the polar region is important in a changing climate, and especially the coastal regions, which is the area that is most sensitive to changes in the climate and contributes to the global sea level rise (Gardner et al., 2013).

In this study, swath processed CryoSat-2 ice surface elevations are validated at four different locations with four different types of validation datasets; The Petermann Glacier and Nioghalvfjerdsfjorden Glacier in Northern Greenland, the Helheim glacier in the Eastern Greenland, and the ice cap of Austfonna located in Svalbard. The validation data consist of X-band radar data, Operation ICEBridge, ICESat-2 laser data, and Airborne Laser Scanner data respectively.

Swath processing improves the radar data coverage compared to conventional retracking, though, the extra amount of data leads to lower signal-to-noise ratio (Foresta et al., 2018), making validation of the swath processed data immensely important. Using different validation datasets allow us to investigate how the validation is impacted by the different platforms’ ability to measure the surface topography.

 

Bibliography:

Foresta L, Gourmelen N, Weissgerber F, Nienow P, Shepherd A and Drinkwater M (2018) Heterogeneous and rapid ice loss over the Patagonian Ice Fields 2 revealed by CryoSat-2 swath radar altimetry. Remote Sensing of Environment, (minorrev(March), 0–1, ISSN 00344257 (doi: 10.1016/j.rse.2018.03.041)

 

Gardner AS, Moholdt G, Cogley JG, Wouters B, Arendt AA, Wahr J, Berthier E, Hock R, Pfeffer WT, Kaser G, Ligtenberg SRM, Bolch T, Sharp MJ, Hagen JO, van den Broeke MR and Paul F (2013) A Reconciled Estimate of Glacier Contributions to Sea Level Rise: 2003 to 2009. Science, 340(6134), 852–857, ISSN 0036-8075 (doi: 10.1126/science.1234532)

 

 
Monitoring plastic accumulation in water hyacinths using remote sensing
Authors: Janssens Niels , Biermann Lauren , Schreyers Louise , Herold Martin , van Emmerik Tim
Published: March 2021

While efforts to quantify plastic waste accumulation in the marine environment are rapidly increasing, the data on plastic transport in rivers are relatively scarce. Rivers are a major source of plastic waste into the oceans and understanding seasonal dynamics of macroplastic transport is necessary to develop effective mitigation measures. Macroplastic transport in rivers varies significantly throughout the year. Research shows that in the case of the Saigon river, Vietnam, these plastic transport fluxes are mainly correlated to the amount of organic debris (mostly water hyacinths). Since large water hyacinths patches can be monitored from space, this gives the opportunity for large scale monitoring using freely available remote sensing products. Remote sensing products, such as Sentinel-2, can be applied to areas where water hyacinths occur and plastic emissions are estimated to be high. In this study, we present a first method to detect and monitor water hyacinths using optical remote sensing. This was done by developing an algorithm to automatically detect and quantify water hyacinth coverage for a large section of the Saigon river in Vietnam, for the year 2018. Spectral signatures of water,  infrastructure in the river, and water hyacinths were used to classify the water hyacinths coverage and dynamics using a Naive Bayes algorithm. Water hyacinths were promisingly identified with 95% accuracy by the Naive Bayes classifier. The comparison between the seasonal dynamics of classified water hyacinth and seasonal dynamics of the field measurements resulted in an overall Pearson correlation of 0.72. The comparison we attempted between seasonal dynamics of plastics from satellite and field measurements yielded a Pearson correlation of 0.48. With the next field campaign collecting in-situ data matched to satellite overpasses, we aim to improve this. In conclusion, we were able to successfully map seasonal dynamics of water hyacinth in an automated way using Sentinel-2 data. Our study provides the first step in exploring the possibilities of mapping water hyacinth from satellite as a proxy for river plastics.
Estimating wildfire emissions of ammonia using Cross-track Infrared Sounder (CrIS) profile information
Authors: Eckert Ellen , Davis Zoe Y. W. , Shephard Mark W. , McLinden Chris A. , Griffin Debora , Tegtmeier Susann , Jia Yue , Cady-Pereira Karen E.
Published: March 2021

Ammonia plays an important role for air, soil and water quality, as well as aerosol formation and plant growth. Accurate estimates of emission rates of ammonia from wildfires are crucial to understand the impact on human health and ecosystems. However, ground-based measurements of ammonia are sporadic. Satellite measurements can help address this monitoring gap. The Cross-track Infrared Sounder (CrIS) product provides a unique tool because some information on the vertical distribution of ammonia is derived from the profile retrievals in addition to vertical column densities (VCDs). Emission rates are retrieved by fitting measured vertical column densities (VCDs) to a three-dimensional function of the wind speed and spatial coordinates. This method requires VCDs to be rotated given the wind-direction to remove wind-direction as a fitting variable. The vertical information given by CrIS provides the potential for more accurate emission estimates as wind-direction and -speed at each profile level can be taken into account. The application of the vertical profile of wind also allows more accurate estimates of plume width, which can vary significantly in the traditional VCD rotation depending on the altitudes of wind used for the rotation. This approach was developed and validated using synthetic satellite measurements of plumes simulated by the FLEXPART (v10.0) model to better understand the impact of variability in the vertical profile of the wind. The methodology was then applied using CrIS satellite observations to estimate forest fire emissions of NH3. Preliminary results of this study will be presented.
In-situ techniques for monitoring drinking water quality
Authors: Elfferich Inge , Bagshaw Elizabeth , Perkins Rupert , Kille Peter , Straiton Sophie , von Benzon Elena
Published: March 2021

Efficient management of drinking water quality is critical for the water supply, so effective monitoring of supply and storage systems is a priority. This project aims to predict the presence of Taste and Odour (T&O) compounds in drinking water reservoirs, using molecular analyses and smart in-situ monitoring systems. The most common T&O compounds, Geosmin and 2-MIB, are secondary metabolites that can be produced in waterbodies by cyanobacteria and actinomycetes and impact drinking water taste and odour. Although there is no evidence of related health risks, they can be perceived by humans at very low concentrations (5-10 ng/L) and the treatment process to remove them from drinking water is costly. Early assessment of T&O risk is crucial, but currently requires time-consuming and costly sampling as well as laboratory analysis which prevents real-time monitoring and a timely management response.

Cyanobacterial species responsible for T&O production can be monitored with eDNA techniques and potentially provide an early warning of T&O episodes. Moreover, detection of the genes that are responsible for T&O production within the DNA of the freshwater community can help to speed up analysis. We show that qPCR methods can target the Geosmin synthase gene (geoA) and that this correlates significantly with Geosmin concentrations >15 ng/L. Alternatively, in-situ sensors that can be deployed remotely and transmit data, can provide real-time monitoring for early warning and potentially predictive capacity. Commercially available sensors do not currently exist for T&O compounds, but they do for many other water quality parameters. We consider the analytes that could be effective for T&O warning systems, using a Welsh reservoir as an exemplar case. Assessment of nutrient dynamics suggests N and P ratios are critical, hence we evaluate the sensors that are available for these compounds and associated environmental controls on their behaviour. We present recommendations for the design of an in-situ monitoring programme and introduce the planned tests that will evaluate it.
Improvement of high resolution measurements of neodymium isotope compositions to reconstruct past ocean circulation
Authors: Rückert Eva M. , Förstel Julius , Frank Norbert
Published: March 2021

Palaeoceanographic studies of ocean circulations are crucial for understanding the ocean´s impact on the Earth´s climate system. Circulation patterns and the provenance of water masses can be detected from temporal variations of the neodymium isotopic composition (εNd) of authigenic neodymium, preserved in deep sea sediment.

Inductively coupled plasma source mass spectrometry allows for the precise and accurate determination of εNd-values of samples and reference material.

Here, we reevaluate the mass spectrometric measurement protocol and instrument setting with respect to precision and accuracy defined by neodymium standards.

The shape of the ion beam plays a crucial role, which is manifested in the result that an optimal adjustment of the beam shaping quadrupoles can increase precision by a factor of 4.

In addition, the optimal standard neodymium concentration level is roughly 50 ppb yielding uncertainties of the mean of repeated measurements as low as 0.07 ε units whereas 5 times lower concentrations yield 10 times higher uncertainties.

The statistical nature of precision is further demonstrated through an uncertainty inversely proportional to the square root of N measurements. As a consequence, with an increase from 30 to 80 consecutive measurements precision was improved by a factor of 1.22.

Taking all evaluated aspects into account, precision and accuracy of standards and thus sediment samples can be strongly improved, hence contributing to a better comprehension of past ocean circulation, where neodymium isotope gradients are small.
Mafic magma as metal source for Sb-W-Hg mineralisation? A case study of the early Carboniferous mafic magmatic event from the French Armorican Variscan belt
Authors: Pochon Anthony , Iacono-Marziano Giada , Erdmann Saskia , Gloaguen Eric , Tuduri Johann
Published: March 2021

A possible genetic link between Sb-W-Hg mineralisation (vein-type and stratabound) and mafic magmatism has been proposed for the Variscan belt during the early Carboniferous, but this hypothesis remains to be rigorously assessed. The metal enrichment of the fluids producing Variscan Sb-W-Hg deposits may be ascribed to (i) crystallization of metal-rich primary mafic magma, and/or (ii) exsolution of metal-rich magmatic fluids and their local concentration, and/or (iii) an efficient hydrothermal leaching of surroundings sedimentary rocks by fluid release due to contact metamorphism. The aim of this project is thus to estimate the contribution of mafic magmas as the metal source of Sb-W-Hg deposits. Our case study focuses on the Saint-Jean-du-Doigt gabbro from the Variscan Armorican belt, Brittany, France. We have characterized the Sb-, W-, and Hg-carrier minerals (e.g. Fe-Ti oxides) and volatile-bearing minerals (e.g. apatite) to quantify the metal content and volatile inventory during purely magmatic and magmatic-hydrothermal processes. Abundant primary amphibole and biotite, and the presence of pegmatoids indicate that the melt was likely to be enriched in volatile. An alteration gradient is observed from the base of the intrusion towards its roof. Moreover, high temperature replacement mineral reactions (e.g. saussuritization) mainly occur in the upper part of the intrusion, suggesting that magmatic fluids were accumulated toward the top of the intrusion. Cathodoluminescence and apatite compositions are taken to record the magmatic-hydrothermal transition and hydrothermal alteration. Apatite ranges in composition between fluorapatite and fluor-hydroxyapatite, but the latter is largely more frequent. A high volatile content of the silicate melt is suggested by the high proportion of negative-shaped fluid inclusions into ilmenite (up to 15 % crystal volume), which hint at a primary magmatic origin. SEM, EPMA and LA-ICP-MS investigations show that magmatic fluid inclusions contain significant amounts of Sb and W. Our results highlight that metals (i.e. Sb, W) were partly partitioned into the fluid phase during magma crystallization and degassing. In addition, trace element content of ilmenite also records metal enrichment from the base to the intrusion roof, probably due to magma degassing and deuteric/metasomatic processes. We therefore propose that mafic magmatism is a potential metal source of the early Carboniferous Sb-W-Hg mineralization event and should be considered as possible sources for other Sb-W-Hg province worldwide. This work was funded by the ANR (ANR-19-MIN2-0002) and author’s institutions in the framework of the ERA-MIN2 AUREOLE project (https://aureole.brgm.fr).
The latest 3D density model of the Barents Sea crust
Authors: Arutyunyan David , Lygin Ivan , Kuznetsov Kirill , Sokolova Tatiana , Shirokova Tatiana , Shklyaruk Alexey
Published: March 2021

The 3D gravity inversion was realized in order to reveal the density features of the Earth's crust the Barents Sea. The original 3D density model of the region includes both lateral and depth density`s changes.
The main steps of the modelling are:

- The calculation of the anomalies of the gravity field in Bouguer reduction with the three-dimensional gravitational effect correction of the seabed.

- Gravity field correction for the three-dimensional influence of the Moho boundary (according to the GEMMA model). The excess density at the Moho picked by minimizing the standard (root-mean-square) deviation of the gravity effect from GEMMA Moho boundary and Bouguer anomalies. So, the regional density jump at the Moho border is 0.4 g / cm3.

- Based on regional geological and geophysical data about the deep structure of the Barents Sea, it was developed generalized dependence of density changes by depth in the sedimentary cover and the consolidated part of the earth's crust.

- Compilation of 3D original model of the base of the sedimentary cover on predictive algorithms of neural networks. The neural network was trained on several reference areas located in different parts Barents area using a number of potential fields transformations and the bottom of the sedimentary cover from model SedThick 2.0.

- Using the resulted dependence of the crust density change by depth and a new model of the sedimentary cover bottom, the gravitational field corrected for the impact of the sedimentary cover with variable density.

- The finally stripped gravity field is used to create density model above and below the base of the sedimentary cover. Frequency filtering on Poisson wavelets [Kuznetsov et al., 2020] had been used for the final separation of the gravitational field into its components.

- The inverse task was solved using specialized volumetric regularization [Chepigo, 2020].

As a result, the crust of the Barents Sea density inhomogeneities were localized by depth and laterally in 3D model, which became the basis for further structural-tectonic mapping.

References

Chepigo L.S. GravInv3D [3D density modeling software]. Patent RF, no. 2020615095, 2020. https://en.gravinv.ru/

Kuznetsov K.M. and Bulychev A.A. GravMagSpectrum3D [Program for spectral analysis of potential fields]. Patent RF, no. 2020619135, 2020.
Deep-water formation and Arctic circulation under sea-ice retreat: a comparison between CMIP6 models
Authors: Bretones Anais , Hestnes  Nisancioglu Kerim , Fjalstad Jensen Mari
Published: March 2021

While a rapid sea-ice retreat in the Arctic has become ubiquitous, the potential weakening of the Atlantic Meridional Overturning circulation (AMOC), in response to rising greenhouse gases, is still under debate. Although climate models predict a weakening of the AMOC, observations are so far inconclusive. It has been suggested that the strength and vertical extent of the AMOC responds to sea-ice retreat, as deep mixing occurs in open-ocean areas close to the sea-ice edge. Here, we investigate this hypothesis by looking at the Arctic tidional Overturning Circulation (ArMOC) and mixed-layer depth in several CMIP6 models forced with the SSP5- 8.5 scenario. For every models we find a decoupling of the ArMOC with the AMOC: while the AMOC weakens during the 21st century, the ArMOC is enhanced.
Riparian forests production related to water supply along southern Hungarian Danube
Authors: Kaizer Benjámin , Gribovszki Zoltán , Kalicz Péter
Published: March 2021

The current climatic conditions of the Hungarian Great Plain is not adequate for the forest cover. Surplus water is essential to maintain good ecological status and growth rate of forests. Moreover, in the drying climate of the Great Plain without excess water the survival of forest vegetation is  questionable.

In this study, we try to indicate the positive effect of the excess water on the growth of the trees next to the Danube in Gemenc wetland (close the southern border of Hungary). The logging data were collected from 2000 to 2009. Sampled forest compartments were clustered into two groups based on the stand position to the levee (exposed to inundation of Danube or not). The effects of the Danube are evaluated using local hydrological measurements (e.g. gauge at Mohács).

The forest growth itself is not the best indicator because it is also influenced by several other ecological variables. To control better these variables two forest stands were selected aged about 110 years. One of them is located behind a summer levee (low crown height levee), which is inundated only by the high floods. Another forest compartment is outside the main levee and never inundated. These stands are sampled to prepare dendrochronological analysis, which gives us higher time-resolution data. We hope these analyses will help us to interpret the relationship between forest growth and water
conditions.

This research has been supported by the Ministry of Agriculture in Hungary.
New tropospheric ozone dataset from OMPS/NPP
Authors: Orfanoz-Cheuquelaf Andrea , Arosio Carlo , Rozanov Alexei , Weber Mark , Ladstätter-Weißenmayer Annette , Burrows John
Published: March 2021

The Ozone Mapping and Profiler Suite, on board of Suomi National Polar-orbiting Partnership (OMPS/NPP) since 2012, features a combination of limb and nadir sensors. This feature allows the use of the limb-nadir matching technique to retrieve tropospheric ozone columns on a global scale, with a single satellite. Using a single instrument avoids additional calibrations and interpolations of the input data for the retrieval. The limb-nadir matching method subtracts the stratospheric ozone column from limb observations (OMPS-LP) from the nadir derived total ozone column (OMPS-NM), using the tropopause height to define the troposphere. Most of the other satellite's retrievals methods are limited either geographically or to a certain altitude range, as e.g. the Convective Cloud Differential method (CCD). In the case of TROPOMI/S5P, the CCD method is used to retrieve tropospheric ozone columns in the tropics, up to 270 hPa.

The single instrument limb-nadir matching was applied for the first time with SCIAMACHY/Envisat (2002-2012). OMPS/NPP provides thus a unique opportunity to extend the time series from SCIAMACHY, in generating a consistent long-term dataset for trend analysis.

Here, we present the new OMPS tropospheric ozone dataset, generated by the limb-nadir matching technique. The dataset is validated using ozonesondes, and compared with the CCD tropospheric ozone product from TROPOMI/S5P, which flies a few minutes apart in the same orbit as OMPS.
Geodetic Investigation of the 30 October 2020 Mw 6.9 Samos-Izmir Earthquake
Authors: Mutlu Bilal , Erol Serdar , Çevikalp Muhammed Raşit , Erol Bihter
Published: March 2021

The earthquake with a magnitude of Mw 6.9 (according to Kandilli Observatory and Earthquake Research Institute-KOERI) occurred 8 km north of Samos Island at a depth of 16 km, on 30.10.2020, at 11:51:24 UTC. It took place on the north-dipping normal fault zone of approximately 40 km length in the sea between Samos Island of Greece and Kuşadası Bay of Turkey. After the mainshock, a tsunami with the height exceeding 1 meter occurred in Seferihisar region, south of Izmir, and north side of Samos Island. In this study, a geodetic investigation of the Samos-Izmir earthquake using GNSS and SAR techniques was carried out. Within the scope of this study, 1Hz observations of Turkey National Continuous GNSS Network-Active (TUSAGA-Aktif) stations in the earthquake zone, were used, and it was aimed to reveal the co-seismic deformation caused by the earthquake. In addition to GNSS data, the InSAR process has been performed by using ESA Sentinel-1 SAR data, and the vertical deformations were clarified with the unwrapped interferogram. The GNSS data were processed using web-based online processing services according to the relative and absolute positioning techniques as static and kinematic modes. In conclusion, considering the absolute and relative static processing of pre- and post-earthquake GNSS data, the maximum horizontal deformations were observed at CESM and IZMI GNSS stations located in the north of the fault. Due to the earthquake, these points moved to the north direction and the maximum horizontal deformations were found as 5.5 cm and 3.5 cm, respectively. According to the kinematic processing of the GNSS data, instantaneous horizontal movements of 12 cm and 4 cm towards the north were observed at the same stations, respectively, at the time of the earthquake. On the contrary, DIDI and AYD1 GNSS stations, which are located in the south of the fault, moved to the south-east direction and the magnitude of horizontal deformations were smaller. Considering the InSAR results, it was seen a 10 cm uplift in the west of the island of Samos and a 10 cm subsidence at the northernmost part. Besides this, a 5 cm subsidence was observed in Izmir territory, the north side of the fault, by means of the interferogram.
Survey of microphysical properties of marine boundary-layer clouds in the Western North Atlantic 
Authors: Kirschler Simon , Voigt Christiane , Ackerman Andrew S. , Anderson Bruce , Chen Gao , Corral Andrea F. , Crosbie Ewan , Dadashazar Hossein , Ferrare Richard A. , Fridlind Ann , Hair Johnathan W. , Li Xiangyu , Moore Richard , Schollmayer Dominik , Shook Michael A. , Thornhill K. Lee , Tornow Florian , Wang Halong , Ziemba Luke D. , Sorooshian Armin
Published: March 2021

Oceanic low level clouds strongly affect the atmospheric radiation budget. Uncertainties in their microphysical properties and cover currently limit the accuracy of climate predictions. Further, studies quantifying the relative importance of aerosol and dynamics on cloud properties in specific meteorological regimes are poorly constrained by observations in the Western North Atlantic boundary layer.

Low level clouds were measured during the Aerosol Cloud meTereology Interactions oVer the western ATlantic Experiment (ACTIVATE) campaign in winter and summer 2020. The two NASA LaRC research aircraft HU-25 Falcon and UC-12 B-200 King Air conducted 35 simultaneous flights to investigate aerosol-cloud interactions of maritime clouds and their impact on radiation. Number concentration, liquid water content, ice water content, and particle size distribution in the size range of 3 µm to 1460 µm in diameter were measured with the fast forward scattering cloud probe (FCDP) and 2-dimensional optical array imaging probe (2D-S) onboard the Falcon. Here, we present an overview of late winter (February-March) and late summer (August-September) oceanic cloud properties in the region 65°W to 80°W and 30°N to 40°N. We compare cloud properties in these two seasons and investigate their dependence on meteorological parameters and aerosol abundance. In a case study, we present cloud observations in a cold air outbreak event on 1 March 2020 with a specific focus on mixed-phase clouds.
Small scale structures in the footprint tails of the Galilean moons observed by JIRAM
Authors: Moirano Alessandro , Mura Alessandro , Adriani Alberto , Sordini Roberto , Migliorini Alessandra , Zambon Francesca , Tosi Federico , Altieri Francesca , Dinelli Bianca Maria , Plainaki Christina , Cicchetti Andrea , Noschese Raffaella
Published: March 2021

The Jovian Infrared Auroral Mapper (JIRAM) on board Juno is a spectro-imager which is observing the
atmosphere of Jupiter and its auroral emission using its two imagers in the L (3.3-3.6μm) and M bands (4.5-
5.0μm) and a spectrometer (2-5 μm spectral range).
The highly elliptic orbit of Juno and the unprecedented resolution of the JIRAM imager allowed to retrieve
wealth of details about the morphology of moon-related aurorae. This phenomenon is due to the jovian magnetic
field sweeping past the Galiean moons, which generate Alfven waves travelling towards the ionosphere and set
up field aligned currents. When the associated electrons reach the ionosphere, they interact with the hydrogen
and make it to glow. In particular, the tails of the footprints showed a spot-like substructure consistently, which
were investigated using the L-band of the imager from perijove 4 to perijove 30. This feature was observed close
to the footprints, where the the typical distance between spots lies between 250km and 500km. This distance
decreases to 150km in a group of three observations in the northern emisphere when each moon is close to 250 ◦
west longitude. No correlation with orbital parameters such as the longitude of the moons was found so far,
which suggests that such morphology is almost purely due to ionospheric processes.
Moreover, during PJ 13 a long sequence of images of the Io footprint was shot and it revealed that the
secondary spots appears to corotate with Jupiter. This behaviour is observed also during orbits 14 and 26.
During these sequences JIRAM clearly observed the Io footprint leaving behind a trail of ”footsteps” as bright
spots.
The characteristics of these spots are incompatible with multiple reflection of Alfven waves between the two
emispheres. Instead, we are currently investigating ionospheric processes like the feedback instability (FI) as a
potential candidate to explain the generation of the observed small scale structure. This process relies on local
enhacement of conductivity in the ionosphere, which is affected by electron precipitation. Order of magnitude
estimates from the FI are compatible with the inter-spot distance and the stillness of the spots.
Testing the application of Permutation Entropy to characterize the precursory phase of volcanic eruptions
Authors: Sudibyo Maria , Eibl Eva , Hainzl Sebastian
Published: March 2021

Permutation Entropy (PE) has been suggested to be a promising tool for the prediction of volcanic eruptions. It is a robust yet simple tool to quantify the complexity of time series. The application has been used in the biomedical and econophysics fields and recently was adopted to find precursors of volcano eruptions and to identify tremor episodes. However, in the different eruption cases, the temporal variation of PE was found behaving in different ways. For example, a gradual drop of PE was observed few days prior to the 1996 Gjalp eruption while it remained high prior to the 2012 Copahua eruption. Our final aim is to quantify what features in the PE can be interpreted as eruption precursors and whether this is applicable to different eruptions from the same or different volcanoes. In calculating the PE, the determination of two key inputs, namely the delay time and the embedding dimension, is crucial as PE depends strongly on those parameters. Here we present several tests on different types of synthetic signals with different signal to noise ratios to determine the most suitable input parameters. We found that when the delay time is much shorter than or equal to the dominant period of the signal, the value of PE will be strongly influenced by the noise. Thus, the value of the delay time should be chosen in between. Furthermore, the embedding dimension should not be smaller than 5 to be able to identify the characteristic of the underlying signal. Finally, we show the application of this method to the seismic data during the dike formation and the effusive eruption at Holuhraun, Iceland, in 2014-2015.
An algorithm for the 3D ROck Slope Kinematic Analysis (ROKA) based on RPAS digital photogrammetry data.
Authors: Menegoni Niccolò , Giordan Daniele , Perotti Cesare
Published: March 2021

Among the several adopted methods for the kinematic analysis of the possible modes of failure that could affect a rock slope, the Markland test is the most used. Whereas, it has the advantage of being simple and fast, it has some limits, as the impossibility to manually consider the several different slope orientations and their interaction with the discontinuity dimensions and positions.

Recently, the improvements in the Remote Piloted Aerial System (RPAS) digital photogrammetry techniques for the development and mapping of Digital Outcrop Models (DOMs) have given the possibility of developing new automatized digital approaches. In this study, ROKA (ROck slope Kinematic Analysis) algorithm is presented. It is an open-source algorithm, written in MATLAB language, which aims to perform the kinematic analysis of the stability of a rock slope using the discontinuity measurements collected onto 3D DOMs. Its main advantage is the possibility to identify the possible critical combination between the 3D georeferenced discontinuities and the local surface of the slope. In particular, the critical combinations that can activate the planar sliding, flexural toppling, wedge sliding and direct toppling modes of failures can be detected and highlighted directly on the DOM. Hence, the ROKA algorithm can make the traditional approach for the kinematic analysis of a rock slope more effective, allowing not only to simplify the analysis, but also to increase its detail. This can be very important, in particular, for the analysis of large and complex rock slopes.
Towards Remote Sensing of Atmospheric Trace Gases in the UV spectral range using Dual-Comb spectroscopy
Authors: Pivard Clément , Galtier Sandrine , Rairoux Patrick
Published: March 2021

The development of increasingly sensitive and robust instruments and new methodologies are essential to improve our understanding of the Earth’s climate and air pollution. In this context, Dual-Comb spectroscopy (DCS) appears as an emerging spectroscopy methodology to detect in situ, without air-sampling, atmospheric trace-gases.

DCS is a Fourier-transform type experiment that takes advantage of mode-locked femtosecond (fs) pulses. This methodology appears highly relevant for atmosphere remote-sensing studies because of its very fast acquisition rate (>kHz) that reduces the impact of atmospheric turbulences on the retrieved spectra. DCS has been successfully applied in near-infrared (NIR) spectral ranges for atmospheric greenhouse gas monitoring (water vapor, carbon dioxide, and methane) [1-2].

Its implementation in the UV range would offer a new spectroscopic intrumentation to target the most reactive species of the atmosphere (OH, HONO, BrO...) as they have their greatest absorption cross-sections in the UV range. UV-DCS would therefore be an answer to the lack of variability of today operationnal and in situ monitoring instrument for those reactive molecules.

We will present a potential light source for remote sensing UV-DCS and discuss the degree of immunity of UV-DCS to atmospheric turbulences. We will show to which extent the characteristics of the currently available UV sources are compatible with the unambiguous identification of UV absorbing gases by UV-DCS. We will finally present the performances of UV-DCS in terms of concentration detection limit for several UV absorbing molecules (OH, BrO, NO2, OClO, HONO, CH2O, SO2). This sensitivity study has been recently published [3] and the main results will be presented.

 

[1] Rieker, G.B.; Giorgetta, F.R.; Swann, W.C.; Kofler, J.; Zolot, A.M.; Sinclair, L.C.; Baumann, E.; Cromer, C.;Petron, G.; Sweeney, C.; et al. « Frequency-comb-based remote sensing of greenhouse gases over kilometer air Paths ». Optica 1, p. 290–298 (2014)

[2] Oudin, J.; Mohamed, A.K.; Hébert, P.J. "IPDA LIDAR measurements on atmospheric CO2 and H2O using dual comb spectroscopy," Proc. SPIE 11180, International Conference on Space Optics — ICSO 2018, p. 111802N (12 July 2019)

[3] Galtier, S.; Pivard, C.; Rairoux, P. Towards DCS in the UV Spectral Range for Remote Sensing of Atmospheric Trace Gases. Remote Sens., 12, p.3444 (2020)
Soil contents and stoichiometry of carbon, nitrogen, and phosphorus in Finnish farmland and feedbacks on management patterns
Authors: Wang Sichu , Uhlgren Oona , Salonen Anna-Reetta , Heinonsalo Jussi
Published: March 2021

The coupled cycles and interactions of soil carbon (C), nitrogen (N), and phosphorus (P) are fundamental for soil quality and soil organic matter (SOM) formation. Low C:N ratios through nitrogenous fertilizer addition may accelerate SOM cycling and promote C mineralization in soil, whereas P limitations may decline C storage by reducing plant and microbial biomass production. Deeper soil layers’ C-N-P stoichiometry has an important role in regulating SOM formation in subsoils. However, there is little information on soil C:N:P stoichiometry in deep soil layers of farmland. In this study, soil columns up to one meter were collected from 32 farms distributing across Finland with different soil texture and agricultural management history. The one-meter soil columns were cut into 10 cm deep slices and analyzed for the total organic carbon (TOC), total nitrogen (TN) by dry combustion method and total phosphorus (TP) contents by aqua regia digestion and ICP-OES method. Overall, the TOC, TN and TP contents all dropped sharply in 30-40 cm soil layers, but TP contents rose again in deep soil. The role of agricultural management practice (including crop rotation, crop cover, crop diversity and fertilization) on soil C:N:P stoichiometry as well as organic matter accumulation in the deep soil layers were explored. The preliminary results will be presented in the poster. The data deepens our understanding of soil C, N and P coupling and interaction related to soil C sequestration.
Observational evidence of urban heat island intensification during heatwaves in European cities
Authors: Possega Marco , Aragão Leonardo , Ruggieri Paolo , Santo Marco Antonio , Di Sabatino Silvana
Published: March 2021

Heatwaves (HWs) are extreme weather conditions characterized by persistent high temperatures with considerable impacts on society in terms of mortality, thermal stress and energy demand of the population. One of the most interesting aspects of HWs concerns the interaction with the phenomenon of urban heat island (UHI). The UHI is the tendency of urbanized areas to have warmer temperatures than the surrounding rural areas, mainly due to the thermal properties of materials forming urban environment and the heat produced by human activities. Some studies analyzed the behavior of UHI during periods of extreme heat, showing an amplification of the gradient of temperature between urban and rural areas in HW conditions, but the results are often limited to case studies with a single HW and/or a specific city. Other papers dealt with the same topic by examining events on various cities using outputs of global models, but with resolution insufficient to include in detail urban-scale processes and therefore to take into account specific properties of the cities investigated. The approach of this work consisted in providing observational evidence and extending the aforementioned results, studying the effect of HWs on UHI in about ten European cities with different characteristics (geography, topography, urban planning) through the analysis of daily maximum/minimum temperatures data measured by meteorological stations for the summers of period 2006-2019. In particular, the intensity of UHI was assessed through the computation of a Composite UHI Index (UHII), defined as the difference between averaged urban and non-urban values. The different behavior of UHII during HWs compared to "normal" summer days (NO) in selected European cities was investigated, detecting an intensification of index values regarding periods of extreme heat for the majority of examined locations. More specifically, the analysis of temporal evolution of UHII was conducted, revealing an average increase of this index during the occurrence of HW events. Moreover, a correlation between UHI index and maximum temperature anomalies was examined, and HW days appeared to exhibit a larger percentage of positive UHII with respect to NO days, showing also higher absolute values. This work provides an indication of how European urban areas respond to severe hot periods and could be useful to validate numerical model simulations for more detailed analysis, for example regarding mitigation strategies. Finally, the emergence of some outliers, namely cities whose UHI manifested a different reaction to HWs, may deserve dedicated studies in the future.
Post-2011 variability of the great Atlantic Sargassum belt attributed to changing winds and currents
Authors: Marsh Robert , Skliris Nikolaos , Oxenford Hazel , Appeaning Addo Kwazi
Published: March 2021

Since 2011, Sargassum seaweed has proliferated across the tropical North Atlantic, evident in Floating Algae Index (FAI) images for the Central Atlantic region (38-63°W, 0-22°N) over 2000-2020. To investigate the role of physical drivers in post-2011 Sargassum blooms, conditions are examined across the wider tropical Atlantic. Of particular consequence for the growth and drift of Sargassum are patterns and seasonality of winds and currents. In years when the FAI index is high (2015, 2018), the Intertropical Convergence Zone (where Sargassum accumulates) was displaced southward, towards nutrient-rich waters of the Amazon river plume and the equatorial upwelling zone. Strong enhancement of the North Brazil Current retroflection and North Equatorial Counter Current circulation system in 2015 and 2018 may have increased nutrient availability/uptake for Sargassum in the North Equatorial Recirculation Region. To first order, these changes are associated with modes of natural variability in the tropical Atlantic, notably a negative phase of the Atlantic Meridional Mode in 2015 and 2018, and a positive phase of the Atlantic Niño in 2018. The influence of anomalous winds and currents on Sargassum drift during years of high and low FAI are explored with virtual particle tracking, using surface currents from an eddy-resolving ocean model hindcast and optional % windage, to quantify the variable partitioning between Sargassum that is westward-bound to the Caribbean and eastward-bound to west Africa.
An analysis of  flow distortion in a multipath sonic anemometer
Authors: Dellwik Ebba , Hummelshøj Poul , Peters Gerhard
Published: March 2021

Sonic anemometers provide point observations of the three-dimensional velocity field at high sampling rates and are crucial instruments for understanding and quantifying the fluxes of momentum, energy and scalars between the atmosphere and Earth’s surface. Since the beginning of sonic anemometry 50 years ago, the characterization of flow distortion, i.e. how the instrument structure alters the flow, has been an ongoing research topic. Multi-path sonic anemometry provides a new opportunity to research and understand flow distortion on the vertical velocity component, since several positions in the small measurement volume can be measured simultaneously. In this work, we use data from a flat terrain measurement campaign in 2020, in which several sonic anemometers were mounted on 4m towers placed 4m apart. The analysis is focused on the Multipath Class-A sonic anemometer (Metek GmbH, Germany), which provides vertical velocity observations from three vertical paths 120 degrees and 0.1m apart. Vertical velocities are also calculated from several combinations of the tilted paths. We investigate how the vertical velocity component is altered depending on wind direction relative to different parts of the instrument structure. We demonstrate that by an optimal combination of the different paths, the vertical velocity variance and fluxes can be significantly enhanced. We also show spectra, and especially look at the high frequency end of the spectrum, where the relative behaviour of the velocity components is known from fundamental turbulence theory. Further, the relative importance of transducer shadowing and pressure-induced blockage effects is discussed.
Phosphate biogeochemical barrier for uranium in situ immobilization in an aquifer nearby sludge repository
Authors: Artemiev Grigory , Safonov Alexey , Popova Nadezhda
Published: March 2021

Uranium migration in the oxidized environment of near-surface groundwater is a typical problem of many radiochemical, ore mining and ore processing enterprises that have sludge storage facilities on their territory. Uranium migration, as a rule, occurs against a high salt background due to the composition of the sludge: primarily, nitrate and sulfate anions and calcium cations. One of the ways to prevent the uranium pollution is geochemical or engineering barriers. For uranium immobilization, it is necessary to create conditions for its reduction to a slightly soluble form of uraninite and further mineralization, for example, in the phosphate form. An important factor contributing to the rapid reduction of uranium is a in the redox potential decreasing and the removal of nitrate ions, which can be achieved through the activation of microflora. It should be added that phosphate itself is one of the essential elements for the development of microflora. This work was carried out in relation to the upper aquifer (7-12 m) near the sludge storage facilities of ChMZ, which is engaged in uranium processing and enrichment. One of the problems of this aquifer, in addition to the high concentration of nitrate ions (up to 15 g / l), is the high velocity of formation waters.
In laboratory conditions, the compositions of injection solutions were selected containing sources of organic matter to stimulate the microbiota development and phosphates for uranium mineralization. When developing the injection composition, special attention was paid to assessing the formation of calcite deposits in aquifer conditions to partially reduce the filtration parameters of the horizon and reduce the rate of movement of formation waters. This must be achieved to ensure the possibility of long-term deposition of uranium and removal of nitrate. The composition of the optimal solution was selected and in a series of model experiments the mineral phases containing the lowest hydrated form of the uranium-containing phosphate mineral meta-otenite were obtained.
In situ mineral phosphate barrier Formation field tests were carried out in water horizon conditions in a volume of 100m3 by injection of an organic and phosphates mixture. As a result, at the first stage of field work, a significant decreasing nitrate ion concentration, and reducing conditions formation coupled with the dissolved uranium concentration of decreasing were noted.
Advancing the simulation of mesoscale eddies: Backscatter schemes in eddy-permitting ocean simulations
Authors: Juricke Stephan , Danilov Sergey , Oliver Marcel , Koldunov Nikolay , Sidorenko Dmitry , Sein Dmitry
Published: March 2021

Capturing mesoscale eddy dynamics is crucial for accurate simulations of the large-scale ocean currents as well as oceanic and climate variability. Eddy-mean flow interactions affect the position, strength and variations of mean currents and eddies are important drivers of oceanic heat transport and atmosphere-ocean-coupling. However, simulations at eddy-permitting resolutions are substantially underestimating eddy variability and eddy kinetic energy many times over. Such eddy-permitting simulations will be in use for years to come, both in coupled and uncoupled climate simulations. We present a set of kinetic energy backscatter schemes with different complexity as alternative momentum closures that can alleviate some eddy related biases such as biases in the mean currents, in sea surface height variability and in temperature and salinity. The complexity of the schemes reflects in their computational costs, the related simulation improvements and their adaptability to different resolutions. However, all schemes outperform classical viscous closures and are computationally less expensive than a related necessary resolution increase to achieve similar results. While the backscatter schemes are implemented in the ocean model FESOM2, the concepts can be adjusted to any ocean model including NEMO.
Does lithology control post-orogenic topography and rock erodibility? Insights from Anti-Atlas of Morocco
Authors: Clementucci Romano , Ballato Paolo , Siame Lionel , Yaaqoub Ahmed , Essaifi Abderrahim , Leanni Laëtitia , Guillou Valery , Faccenna Claudio
Published: March 2021

Rock erodibility plays a central role in setting topographic limits on relief development and is a key parameter in landscape evolution models. However, channel bed erodibility (K) is usually either fixed arbitrary or let varying over a wide range of values (10-12 – 10-3) because it is difficult to estimate. The topography of ancient orogens offers favourable conditions to quantify bedrock erodibility through the stream profile analysis, because the channel steepness is directly related to rock erodibility rather than rock uplift or climate variability.

The Anti-Atlas is a Variscan (Paleozoic) orogen of NW Africa that has not been drifted for long distances over the late Cenozoic and hence has not experienced an extended shift across climatic zones. Furthermore, it is characterized by a well preserved uplifted relict landscape with rather uniform erosion rates since at least the last 120 - 100 Ma. This specific configuration allows studying in detail landscape erosional dynamics and erodibility.

Here, we combine geomorphic analysis of stream profiles with in situ-produced cosmogenic concentrations (10Be) in river sediments, to decipher the surface evolution of the AntiAtlas and the adjacent Siroua Massif. In the Anti-Atlas, the basin-wide denudation rates determined for the relictal part of the landscape range between 5 and 20 m Ma-1, consistent with rates estimated from the volume of volcanics eroded from the Siroua Massif during the last 12 - 10 Ma (10 to 20 m Ma-1). The close agreement of short- and long-term erosion rates suggests a steady state landscape.

Our results demonstrate the main role of rock-type on sustaining post-orogenic landscape. Specifically, we find a striking correlation between erosion rates and normalized channel steepness per different rock-types. This allows estimating the erodibility within a narrower range of values (10-7 - 10-4) as a function of the reference concavity values of the river network.