bluuebunny/crossref_metadata_2025 huggingface dataset:
Springtime nitrogen oxides and tropospheric ozone in Svalbard: local and long-range transported air pollution
Authors: Dekhtyareva Alena , Hermanson Mark , Nikulina Anna , Hermansen Ove , Svendby Tove , Holmén Kim , Graversen Rune
Published: March 2021

Svalbard is a near pristine Arctic environment, where long-range transport from mid-latitudes is an important air pollution source. Thus, several previous studies investigated the background nitrogen oxides (NOx) and tropospheric ozone (O3) springtime chemistry in the region. However, there are also local anthropogenic emission sources on the archipelago such as coal power plants, ships and snowmobiles, which may significantly alter in situ atmospheric composition.  Measurement results from three independent research projects were combined to identify the effect of emissions from various local sources on the background concentration of NOx and O3 in Svalbard. The hourly meteorological and chemical data from the ground-based stations in Adventdalen, Ny-Ålesund and Barentsburg were analysed along with daily radiosonde soundings and weekly data from O3 sondes. The data from the ERA5 reanalysis were used to evaluate the prevailing synoptic conditions during the fieldwork. Although the correlation between the NOx concentrations in the three settlements was low due to dominant influence of the local atmospheric circulation, cases with common large-scale meteorological conditions increasing the local pollutant concentration at all sites were identified. In colder and calmer days and days with temperature inversions, the concentrations of NOx were higher. In contrast to NOx values, O3 concentrations in Barentsburg and at the Zeppelin station in Ny-Ålesund correlated strongly, and hence the prevailing synoptic situation and long-range transport of air masses were controlling factors for them. The Lagrangian models HYSPLIT and FLEXPART have been used to investigate air mass transport and transformations during the large scale O3 depletion and enrichment events. The factors affecting Arctic springtime photochemistry of O3 have been investigated thoroughly using Lagrangian and Eulerian numerical weather prediction model data and Metop GOME-2 satellite observations.
Characteristics and variability of ocean ventilation in the high-latitude North Atlantic in an eddy-permitting ocean model
Authors: Johnson Helen L. , MacGilchrist Graeme , Marshall David P. , Lique Camille , Thomas Matthew , Jackson Laura , Wood Richard
Published: March 2021

A substantial fraction of the deep ocean is ventilated in the high latitude North Atlantic. As a result, the region plays a crucial role in transient climate change through the uptake of carbon dioxide and heat. We investigate the nature of ventilation in the high latitude North Atlantic in an eddy-permitting numerical ocean circulation model using a set of comprehensive Lagrangian trajectory experiments. Backwards-in-time trajectories from a model-defined ‘North Atlantic Deep Water’ (NADW) reveal the times and locations of subduction from the surface mixed layer at high temporal and spatial resolution. The major fraction (∼60%) of NADW ventilation results from subduction directly into the Labrador Sea boundary current, with a smaller fraction (∼25%) arising from open ocean deep convection in the Labrador Sea. There is a notable absence of ventilation arising from subduction in the Greenland–Iceland–Norwegian Seas, due to the re-entrainment of those waters as they move southward. Temporal variability in ventilation arises both from changes in subduction — driven by large-scale atmospheric forcing — and from year-to-year changes in the subsurface retention of newly subducted water, the result of an inter-annual equivalent of Stommel’s mixed layer demon. This interannual demon operates most effectively in the open ocean where newly subducted water is slow to escape its region of subduction. Thus, while subduction in the boundary current dominates NADW ventilation, processes in the open ocean set the variability, mediating the translation of inter-annual variations in atmospheric forcing to the ocean interior.
SIOS’s airborne remote sensing campaigns in Svalbard 
Authors: Jawak Shridhar , Sivertsen Agnar , Pohjola Veijo , Błaszczyk Małgorzata , Kohler Jack , Tømmervik Hans , Nilsen Lennart , Majerska Marta , Kræmer Thomas , Loonen Maarten J.J.E. , Søreide Janne , Ignatiuk Dariusz , Godøy Øystein , Jennings Inger , Hübner Christiane , Lihavainen Heikki
Published: March 2021

Svalbard Integrated Arctic Earth Observing System (SIOS) is an international collaboration of 24 research institutions from 9 countries studying the environment and climate in and around Svalbard. The global pandemic of Coronavirus disease (Covid-19) has affected the Svalbard research in a number of ways due to nationwide lockdown in many countries, strict travel restrictions in Svalbard, and quarantine regulations. Many field campaigns to Svalbard were cancelled in 2020 and campaigns in 2021 are still uncertain. In response to this challenge, we conducted practical activities to support the Svalbard science community in filling gaps in scientific observations. One of our activities involved conducting airborne remote sensing campaigns in Svalbard to support scientific projects. In 2020, SIOS supported 10 scientific projects by conducting 25 hours of aircraft and unmanned aerial vehicle (UAV)-based data collection in Svalbard. This is one of the finest ways to fill the data gap in the current situation as it is practically possible to conduct field campaigns using airborne platforms in spite of travel restrictions. We are using the aerial camera and hyperspectral sensor installed onboard the Dornier DO228 aircraft operated by the local company Lufttransport to acquire aerial images and hyperspectral data from various locations in Svalbard. The hyperspectral sensor image the ground in 186 spectral bands covering the range 400-1000 nm. Hyperspectral data can be used to map and characterise earth, ice and ocean surface features, such as minerals, vegetation, glaciers and snow cover, colour and pollutants. Further, it can be used to make 3D models of the terrain as well as searching for the presence of animals (e.g. counting seals). In addition, aerial photos are particularly useful tool to follow the seasonal dynamic changes and extent in sea ice cover, tracking icebergs, ocean productivity (Chlorophyll a) and river runoff (turbidity). Data collected from the SIOS funded airborne missions will not only help to fill a few of the data gaps resulting from the lockdown but also will be used by glaciologists, biologists, hydrologists, and other Earth system scientists to understand the state of the environment of Svalbard during these times. In 2021, we are continuing this activity by conducting more airborne campaigns in Svalbard. In this presentation, we will specifically focus on the overview of projects supported by airborne remote sensing campaigns.
Using multi-scale modeling and observations to link the eruption source parameters to the dispersion of volcanic clouds in case of the Raikoke eruption 2019
Authors: Bruckert Julia , Hoshyaripour Gholam Ali , Horváth Ákos , Muser Lukas , Prata Fred J. , Hoose Corinna , Vogel Bernhard
Published: March 2021

The Raikoke volcano emitted about 0.4-1.8 x 10⁹ kg of ash and 1-2 x 10⁹ kg of SO2 up to 15 km into the atmosphere. However, the eruption was characterized by several puffs of different time periods and eruption heights. Here, we use the ICON-ART model in a model setup in which we resolve the phases of the Raikoke eruption. We calculated the eruption source parameters (ESPs) online by coupling ICON-ART to the 1-D plume model FPlume. The input heights for the different eruption phases needed for FPlume are geometrically derived from GEOS-17 satellite data. An empirical relationship is used to derive the amount of very fine ash (particles <32µm) which is relevant for long range transport in the atmosphere. In the first hours during and after the eruption, the modeled ash loading agrees very well with the observed ash loading from Himawari-8 due to the resolution of the eruption phase and the online calculation of the ESPs. In later hours, aerosol dynamical processes (nucleation, condensation, coagulation) explain the loss of ash in the atmosphere in agreement with the observations. However, a direct comparison is partly hampered by water and ice clouds overlapping the ash cloud in the observations. In case of SO2, we compared 6-hourly means of model and Himawari data with respect to the structure, amplitude, and location (SAL-method). In the beginning, the structure and amplitude values differed largely because the dense ash cloud directly after the eruption leads to an underestimation of the SO2 amount in the satellite data. On the second and third day, the SAL values are close to zero for all parameters indicating a good agreement of model and observations. We argue that representing the plume phases and ESPs in ICON-ART by FPlume enhances ash and SO2 predictability in the first days after the eruption, especially in case of non-continuous volcanic eruptions like the Raikoke eruption 2019.
The Isotopic Composition of Cyprus Precipitation. A Tool of Isotope Hydrology.
Authors: Christofi Christos , Bruggeman Adriana , Kuells Christoph
Published: March 2021

Monitoring and profiling the isotopic composition of soil water in combination with groundwater isotope hydrology are commonly used in studying flow and transport in soils as well as in estimating groundwater recharge. Establishing the isotopic composition of local precipitation is of essence. Towards this end and in facilitating the application of isotope hydrology in Troodos Fractured Aquifer (TFA), precipitation was monitored in 16 precipitation sampling stations, stretching from the shoreline up to 1725 m above m.s.l., from January of 2015 to December of 2017. A seasonal trend was discerned, with isotopically depleted rainfall occurring in December as opposed to the more enriched autumn and spring rainfall. Northern European air masses appear to prevail during the months of December to January during which d values tend to be on average above 25‰ whereas the more enriched rain with the lowest d values occurs in July. The averaged seasonal effect between 2015 and 2017 on δ18O, δ2H and d values are 4.53‰, 30.98‰ and 14.93‰, respectively. Cyprus’ Local Meteoric Water Line (LMWL) was found to be equal to δ2H = (6.58±0.13)*δ18O + (12.64±0.91) and a general decrease of 1.22‰ for δ2H and 0.20‰ for δ18O in precipitation was calculated per 100 m altitude.  Similar values have been found by other researchers for the region. These variations in the isotope composition of rainfall can be used to earmark seasonal input of recharge water and for deriving percolation rates from tracing their movement in the soil column.
Trends inflate estimates of subseasonal skill for surface temperatures
Authors: Wulff Ole , Vitart Frédéric , Domeisen Daniela
Published: March 2021

Subseasonal-to-seasonal (S2S) predictions have numerous applications and improving forecast skill on this time scale has become a major effort. Since forecast uncertainty is high on S2S lead times, ensemble prediction systems are essential in order to provide probabilistic forecasts, informing about the range of possible outcomes. For evaluating their performance, these forecasts are routinely compared to a climatological reference forecast. The climatological distribution is commonly assumed to be stationary over the verification period. However, prominent deviations from this assumption exist, especially considering trends associated with climate change. Using synthetic forecast-verification pairs we show that estimates of the probabilistic skill of both continuous and categorical forecasts with a fixed actual level of skill increase as a function of the variance explained by the trend over the hindcast period. The skill of categorical forecasts can be inflated even further when evaluated over a longer forecast period. We also show that this skill enhancement can be observed in the ECMWF extended-range ensemble prediction system. We demonstrate that the effects on the skill in an operational forecast setting are currently strongest in the tropics and mainly relevant for categorical forecasts. This highlights that care needs to be taken when evaluating forecasts that are subject to non-stationarity on time scales much longer than the forecast verification window, especially for categorical forecasts. The results presented in this study are by no means limited to the S2S time scale but have similar implications for the verification of seasonal to decadal predictions, where the existence of trends can further inflate forecast skill.
Isotope systematics (Pb-Nd-Sr) and LA-ICP-MS (REE, Os, PGE) data on time, duration and origin of Paleoproterozoic complex deposits in the N-E part of the Arctic region, Fennoscandian Shield
Authors: Bayanova Tamara , Serov Pavel , Drogobuzhskaya Svetlana
Published: March 2021

The isotope U-Pb system on zircon and baddeleyite reflects the precise age of the origin (2.5, 2.45 and 2.4 Ga) and duration (more than 100 Ma) for Cu-Ni and PGE complex deposits widespread in the N-E part of the Fennoscandian Shield. The Monchegorsk, Fedorovo-Pansky and Mt. Generalskaya layered intrusions and ore regions of the orthomagmatic Cu-Ni and PGE deposits with Pt-Pd reefs originated on the continental crust (3.7 Ga). Main phases of gabbronorites were formed mainly at 2.5 Ga and secondary anorthosites at 2.45 Ga, according to U-Pb data on zircon-baddeleyite geochronometries. The Imandra lopolith with Cr deposits was active from 2.45 Ga to 2.4 Ga due to dyke deformation complexes. Isotope Sm-Nd studies and investigations of rock-forming and sulphide minerals from the deposits indicated coeval ages and 3 magmatic time activity with positive epsilon Nd. Deformation or metamorphic events were dated using the Rb-Sr system on minerals and whole rocks from the deposits at 1.9-1.8 Ga.

The Pados Cr (2.08 Ga), Pechenga Cu-Ni (1.98 Ga) and Kolvitsa Ti-Mg (1.89 Ga) orthomagmatic deposits were dated, using the Pb-Nd-Sr isotope systematics. The mentioned deposits originated probably on the oceanic crust (2.7 Ga). According to new in situ LA-ICP-MS data on Os, PGE and REE concentration in zircon, baddeleyite and sulphide minerals from the complex deposits are characterized by subchondritic sources (Malitch et al., 2019). Paleoproterozoic layered intrusions (2.5-1.8 Ga) and deposits were formed from the plume enrichment mantle reservoir (EM-1), according to Nd-Sr data on whole rocks. Baddeleyite as a mantle mostly mineral (Zircon, 2003) reflects the continental break-up and is connected with the oldest supercontinental reconstruction (Ernst, 2016).

All studies have been supported by RFRB 18-05-70082, Scientific Research Contracts Nos 0226-2019-0032 and 0226-2019-0053.
Deforestation impacts on Amazon-Andes hydroclimatic connectivity
Authors: Sierra Juan , Espinoza Jhan Carlo , Junquas Clementine , Polcher Jan , Saavedra Miguel , Molina Carpio Jorge Alcides , Andrade Marcos , Condom Thomas , Ticona Laura
Published: March 2021

The Amazon rainforest is a key component of the climate system and one of the main planetary evapotranspiration sources. Over the entire Amazon basin, strong land-atmosphere feedbacks cause almost one third of the regional rainfall to be transpired by the local rainforest. Maximum precipitation recycling ratio takes place on the southwestern edge of the Amazon basin (a.k.a. Amazon-Andes transition region), an area recognized as the rainiest and biologically richest of the whole watershed. Here, high precipitation rates lead to large values of runoff per unit area providing most of the sediment load to Amazon rivers. As a consequence, the transition region can potentially be very sensitive to Amazonian forest loss. In fact, recent acceleration in deforestation rates has been reported over tropical South America. These sustained land-cover changes can alter the regional water and energy balances, as well as the regional circulation and rainfall patterns. In this sense, the use of regional climate models can help to understand the possible impacts of deforestation on the Amazon-Andes zone.

This work aims to assess the projected Amazonian deforestation effects on the moisture transport and rainfall behavior over tropical South America and the Amazon-Andes transition region. We perform 10-year austral summer simulations with the Weather Research and Forecasting model (WRF) using 3 one-way nested domains. Our finest domain is located over the south-western part of the basin, comprising two instrumented Andean Valleys (Zongo and Coroico river Valleys). Convective permitting high horizontal resolution (1km) is used over this domain. The outcomes presented here enhance the understanding of biosphere-atmosphere coupling and its deforestation induced disturbances.
Intra-annual climatic signal in tree rings of Larix sp. based on the Vaganov-Shashkin model output
Authors: Fonti Marina , Churakova (Sidorova) Olga , Tychkov Ivan
Published: March 2021

Air temperature increase and change in precipitation regime have a significant impact on northern forests leading to the ambiguous consequences due to the complex interaction between the ecosystem plant components and permafrost. One of the major interests in such circumstances is to understand how tree growth of the main forest species of the Siberian North will change under altering climatic conditions. In this work, we applied the process-based Vaganov-Shashkin model (VS - model) of tree growth in order to estimate the daily impact of climatic conditions on tree-ring width of larch trees in northeastern Yakutia (Larix cajanderi Mayr.) and eastern Taimyr (Larix gmelinii Rupr. (Rupr.) for the period 1956-2003, and to determine the extent to which the interaction of climatic factors (temperature and precipitation) is reflected in the tree-ring anatomical structure. Despite the location of the study sites in the harsh conditions of the north, and temperature as the main limiting factor, it was possible to identify a period during the growing season when tree growth was limited by lack of soil moisture. The application of the VS-model for the studied regions allowed establishing in which period of the growing season the water stress is most often manifest itself, and how phenological phases (beginning, cessation, and duration of larch growth) vary among the years.

The research was funded by RFBR, Krasnoyarsk Territory and Krasnoyarsk Regional Fund of Science, project number 20-44-240001 and by the Russian Ministry of Science and Higher Education (projects FSRZ-2020-0010).
Impact of climatic step-changes on source-to-sink systems: Petrographic changes across the Permian-Triassic changes on the Finnmark Platform, Barents Sea, N Norway
Authors: Kling Melanie , Sirevaag Hallgeir , Pucéat Emmanuelle , Eide Christian Haug
Published: March 2021

The emplacement of the Siberian Traps Large Igneous Province around the Permian–Triassic boundary significantly affected both climate and depositional environments across the world. Known long term consequences of this event are (I) global warming, (II) increased continental weathering, (III) oceanic stagnation and acidification and (IV) mass extinction. These effects have the potential to strongly alter signals from source-to-sink systems in terms of petrography, sediment volumes and geochemistry. The Barents Sea Basin is an excellent area to investigate the response of source-to-sink systems to such climatic changes because it contains a continuous record of sediments deposited before, during and after the Permian-Triassic event, and because this interval is sampled in several exploration wells.

The goal of this project is to investigate how the Triassic climatic changes were expressed in source-to-sink systems, mainly using techniques such as facies analysis, petrograpy, mudstone geochemistry and sediment volumes. Herein we present preliminary results mainly from sandstone petrology. On the Finnmark Plattform, the upper Permian strata of the Røye Formation contains spiculitic mudstones and limestones with sparse sandstones. These are overlain by mudstones, interbedded turbidites and prograding deltas of the Lower Triassic. In order to determine how the signal from the catchment changed to the great climatic changes, it is of high importance to examine changes within provenance and sediment volumes across the P-T boundary.

I wish to give this presentation as a poster
Slab segmentation and continental collision: reconstructing slab deformation in South-East Iran during the closure of Neotethys. 
Authors: Creighton Reuben , Spakman Wim , Lister Gordon
Published: March 2021

As the Arabian continent converged with Eurasia during the closure of Neotethys, the subducting slab of oceanic lithosphere deformed and tore into segments. In the Makran subduction zone, ongoing rollback and extension within a convergent setting was accommodated by subduction zone bounding strike-slip systems. A 3D slab model for the subducted lithosphere in the Makran region was constructed using eQuakes and SKUA-GOCAD, based on the UU-P07 tomographic velocity model, and the available records of modern seismic activity. Seismotectonic analysis suggests remnants of subducted slab within the adjacent collision zone influence active tectonics. Slab floating and analysis of the morphology of the model suggests potential sites of slab tearing, which are evaluated against the record of regional magmatism. The slab model also allows for the examination of proposed models for subduction against the magnitude and location of reconstructed lithosphere.
Superposed Epoch Analyses of electron-driven and proton-driven magnetic dips
Authors: Zhu Hui , Chen Lunjin
Published: March 2021

In this study, we use the Van Allen Probes data statistically to investigate the features of magnetic dips by the means of superposed epoch analysis. Based on the different max values of electron and proton plasma betas, we categorize the dips into two types: electron-driven dips and proton-driven dips. Superposed epoch analysis on two types of magnetic dips suggests the correlation between the magnetic fluctuations and plasma betas. Moreover, the occurrence of the butterfly distributions of relativistic electrons driven by the magnetic dips is confirmed by the statistical results. Our results reveal the statistical characteristics of magnetic dips and build up the relationship among the magnetic fluctuations and several parameters, indicating the potentially important role of magnetic dips in the dynamics of the inner magnetosphere.
Machine Learning Parameterization of Mature Tropical Cyclone Boundary Layer
Authors: Wang Le-Yi , Tan Zhe-Min
Published: March 2021

Tropical cyclone (TC) is among the most destructive weather phenomena on the earth, whose structure and intensity are strongly modulated by TC boundary layer. Mesoscale model used for TC research and prediction must rely on boundary layer parameterization due to low spacial resolution. These boundary layer schemes are mostly developed on field experiments under moderate wind speed. They often underestimate the influence of shear-driven rolls and turbulences. When applied under extreme condition like TC boundary layer, significant bias will be unavoidable. In this study, a novel machine learning model—one dimensional convolutional neural network (1D-CNN)—is proposed to tackle the TC boundary layer parameterization dilemma. The 1D-CNN saves about half of the learnable parameters and accomplishes a steady improvement compared to fully-connected neural network. TC large eddy simulation outputs are used as training data of 1D-CNN, which shows strong skewness in calculated turbulent fluxes. The data skewness problem is alleviated in order to reduce 1D-CNN model bias. It is shown in an offline TC boundary layer test that our proposed model, the 1D-CNN, performs significantly better than popular schemes now utilized in TC simulations. Model performance across different scales is essential to final application. It is found that the high resolution data contains the information of low resolution data but not vise versa. The model performance on the extreme data is key to final performance on the whole dataset. Training the model on the highest resolution non-extreme data plus extreme data of different resolutions can secure the robust performance across different scales.
Spatial changes in inclusion band spacing as an indicator of temporal changes in slow earthquake recurrence intervals
Authors: Nishiyama Naoki , Ujiie Kohtaro , Kano Masayuki
Published: March 2021

Repeated slow earthquakes downdip of the seismogenic zones may trigger megathrust earthquakes by transferring stress to the seismogenic zones. Geodetic observations have suggested that the recurrence intervals of slow earthquakes decrease toward a next megathrust earthquake. However, the temporal variation in recurrence intervals of slow earthquakes during megathrust earthquake cycles remains poorly understood due to the limited duration of geodetic and seismological monitoring of slow earthquakes. The quartz-filled, crack-seal shear veins in the subduction mélange deformed near the downdip limit of seismogenic zone in warm-slab environments record the cyclic changes in the inclusion band spacing in the range of 5–65 μm. The two-phase primary fluid inclusions in quartz between inclusion bands show various vapor/liquid ratios regardless of inclusion band spacing, suggesting a common occurrence of fast quartz sealing due to a rapid decrease in quartz solubility associated with a large fluid pressure reduction. A kinetic model of quartz precipitation, considering a large fluid pressure change and inclusion band spacings, indicates that the sealing time during a single crack-seal event cyclically decreased and increased in the range of 0.2–2.7 years, with minimum one cycle duration estimated to be 31–93 years. The ranges of sealing time and one cycle duration may be comparable to the recurrence intervals of slow earthquakes and megathrust earthquakes, respectively. We suggest that the spatial change in the inclusion band spacing is a potential geological indicator of the temporal changes in slow earthquake recurrence intervals, particularly when large fluid pressure reduction occurred by brittle fracturing.
Adjoint Seismic Tomography of the Antarctic Continent Incorporating Green's Functions from Ambient Noise Correlation
Authors: Zhou Zhengyang , Wiens Douglas , Lloyd Andrew
Published: March 2021

The Antarctic continent with its large ice sheets provides a unique environment to investigate the response of the solid Earth to ice mass change. A key requirement of such studies is high-resolution seismic images of the crust and upper mantle, which can be used to estimate the region’s viscous structure. Likewise, these images are key to understanding the region’s geologic history and underlying geodynamic processes. Although the existing transverse isotropic seismic model ANT-20(Lloyd et al., 2020) and azimuthally anisotropic seismic model ANT-30 (Lloyd et al., in prep) have regional-scale resolution from the upper mantle to the transition zone, there is a need for higher resolution within the uppermost mantle (< 75 km) and crust of Antarctica. In this study, we use the ANT-30 model (Lloyd et al., in prep), a 3D seismic model from earthquake data, as a starting model. We seek to improve its resolution within the upper ~100 km of the Antarctic mantle by fitting three-component ambient noise correlograms computed from broadband records collected in Antarctica over the past 20 years. This includes data from recent temporary arrays such as TAMSEIS, AGAP, TAMNNET, RIS, POLENET/ANET, and UKANET. The three-component cross-correlations of station pairs are calculated and properly rotated to extract ambient noise surface waves that include both Rayleigh and Love waves, which show excellent signal-to-noise ratio between 15 to 70 seconds. The benefit of including this data is twofold: (1) it provides surface wave observations down to 15 s, as opposed to 25 s and (2) it provides shorter intercontinental paths, which were absent due to the region’s earthquake distribution. We then use the software package SPECFEM3D_GLOBE to iteratively improve the 3-D earth model, minimizing the nondimensionalized traveltime phase misfit between the observed and synthetic waveforms. The preliminary results indicate a stronger positive radial anisotropy (VSH > VSV) in the lower crust and uppermost mantle for West Antarctica and part of East Antarctica.  With more iterations, smaller-scale detail can be revealed by the new ambient noise data, resulting in a more reliable uppermost mantle and crustal structure.
Impact of tropical tropopause layer cooling trend on extreme deep convection in Asian-African sector
Authors: Kodera Kunihiko , Eguchi Nawo , Ueyama Rei , Funatsu Beatriz , Gaetani Marco , Taylor Christopher
Published: March 2021

Previous studies have suggested that the recent increase in tropical extreme deep convection, in particular over Asia and Africa during the boreal summer, has occurred in association with a cooling in the tropical lower stratosphere. The present study is focused on the Sahel region of West Africa, where an increased occurrence of extreme precipitation events has been reported over recent decades. The results show that the changes since the 1980s involve a cooling trend in the tropical lower stratosphere and tropopause layer, combined with a warming in the troposphere. This feature is similar to that which might result from increased greenhouse gas levels. It is suggested that the decrease in the vertical temperature gradient in the tropical tropopause region enhances extreme deep convection where penetrating convection is frequent, whereas tropospheric warming suppresses the shallower convection. The essential feature of the recent changes over the tropics is therefore the depth of convection, rather than the total amount of surface precipitation. This could enhance cooling in the lower stratosphere through decrease in ozone concentration.

 
Drought variability driven by interannual and decadal teleconnection patterns in monsoon regions of Southeast China 
Authors: Chun Kwok Pan , He Qing , Dieppois Bastien , Pohl Benjamin , Yetemen Ömer , Chen Liang , Yang Qing , Şen Ömer Lütfi , Çağlar Ferat , Klaus Julian , Massei Nicolas
Published: March 2021

Drought conditions of Southeast China are associated with the sea surface temperature warm pool in the tropical Western Pacific, which is related to low-frequency hydroclimatic patterns and their teleconnections. Empirically, the moisture influx to the region is linked to the interannual and decadal teleconnections, including the Pacific Decadal Oscillation (PDO), the Pacific-Japan Oscillation (PJO) and the Silk Road Pattern (SRP). However, it is still unclear how those teleconnection patterns affect drought conditions in Southeast China via changes in monsoons’ dynamics or wave activities. In this study, we use ERA5 reanalysis over the 1950-2019 period to explore the impacts of the PDO, PJO and SRP on Asian monsoons’ dynamics and regional drought conditions over Southeast China, based on a self-calibrating Palmer Drought Severity Index (scPDSI). We specially use station data from the Greater Bay Area (GBA) which is a national key region for development in Southeast China which is affected by seasonal droughts in winters. Results indicate that drought conditions in Southeast China are significantly related to monsoons: the East Asia Monsoon (EAM), the Western North Pacific Monsoon (WNPM) and the Webster-Yang Monsoon (WYM), between 1950-2019. The strength of monsoons is modulated by PDO, PJO and SRP. A negative phase of SRP corresponds to a southward shift of the Asian westerly jet, strengthening winter Asian monsoons and causing drier conditions in the GBA. Similarly, a cold phase of PDO contributes to drier conditions in the GBA, by weakening Asian monsoons. For the negative phase of PJO, the trade wind of the Walker cell is weakened by the meridional pressure dipole over the West Pacific adjacent to the Southeast China coast. This pressure dipole reduces moisture influx to the continent by the weakened trade wind and leads to less precipitation over East China. Such three climate factors are also interacted through the modulations of monsoons and wave-activities. An extension of the Eliassen-Palm (EP) flux shows that the SRP relates to convective and dynamic wave-activities, which could explain changes in monsoons’ dynamics and drought conditions in Southeast China. To investigate the future drought conditions over Southeast China, bias-corrected historical and RCP8.5 scenarios are used for six of the Coupled Model Intercomparison Project Phase 5 (CMIP5) models (i.e. ACCESS1, BCC, CNRM, IPSL, MPI, and GFDL) between 1861-2100. Among six models, IPSL and GFDL models reproduce the teleconnections well between changes in the monsoons and drought conditions over the GBA, for both historical simulations and future projections. Our results provide insights into the mechanisms of teleconnection patterns affecting drought monitoring and risk management in Southeast China. 
Subgrid modelling of ion pitch-angle scattering for magnetosheath waves in a global hybrid-Vlasov simulation
Authors: Dubart Maxime , Ganse Urs , Osmane Adnane , Johlander Andreas , Battarbee Markus , Alho Markku , Bussov Maarja , George Harriet , Grandin Maxime , Papadakis Kostis , Pfau-Kempf Yann , Suni Jonas , Turc Lucile , Palmroth Minna
Published: March 2021

Numerical simulations are widely used in modern space physics and are an essential tool to understand or discover new phenomena which cannot be observed using spacecraft measurements. However, numerical simulations are limited by the space grid resolution of the system and the computational costs of having a high spatial resolution. Therefore, some physics may be unresolved in part of the system due to its low spatial resolution. We have previously identified, using Vlasiator, that the proton cyclotron instability is not resolved for grid cell sizes larger than four times the inertial length in the solar wind, for waves in the downstream of the quasi-perpendicular shock in the magnetosheath of a global hybrid-Vlasov simulation. This leads to unphysically high perpendicular temperature and a dominance of the mirror mode waves. In this study, we use high-resolution simulations to measure and quantify how the proton cyclotron instability diffuses and isotropizes the velocity distribution functions. We investigate the process of pitch-angle scattering during the development of the instability and propose a method for the sub-grid modelling of the diffusion process of the instability at low resolution. This allows us to model the isotropization of the velocity distribution functions and to reduce the temperature anisotropy in the plasma while saving computational resources.
A GIS-based assessment of spatial groundwater quality for drinking purposes in Asmara City, Eritrea
Authors: Asghede Kabral Mogos , Hagos Dawit Berhane
Published: March 2021

Abstract: Presently the water-supply problem in the Asmara area has reached to a critical level. Using a GIS-based method this study identifies the spatial variability of the groundwater quality in the Asmara Area which could be an alternative source. The results show that, the Total Dissolved Solids (TDS), Total Hardness (TH), Chloride (Cl-), Nitrates (NO3-), Calcium (Ca), Magnesium (Mg), Sulphate (SO4) and pH are 791.71, 569.12, 124.41, 64.46, 155.60, 46.64, 159.26 and 7.72 mg/L, respectively. Moreover, the zone map of the developed groundwater quality shows that the potable water without treatment covers about 35%, and the potable water in the absence of better alternate sources covers about 58% of the total area. The remaining, 7.04% of the total, falls under non-potable groundwater quality. The verification of the spatialanalysis demonstrates that the framework is the first one in Eritrea and could be used as a potential prediction for the assessment of the spatial groundwater quality in the countries with further verification results. Hence, the delineation of groundwater quality zones and establishment of a GIS-based database will easily help the decision makersto monitor and plan the utilization of the groundwater resources in the study area.

Keywords: Groundwater quality; physicochemical parameters; GIS spatial analysis; framework
Mineralogical characterisation and deportment studies of different mine waste material from a historic tailings pond in Plombières, East Belgium.
Authors: Bevandić Srećko , Muchez Philippe , Blannin Rosie , Bachmann Kai , Frenzel Max , Gomez Escobar Alexandra , Pinto Álvaro , M. R. S. Relvas Jorge
Published: March 2021

Recent studies on historic mine waste (e.g. tailings, waste rock, metallurgical waste) indicate the recycling potential of the material for metal extraction. Historic mine wastes have been shown to be of more interest than modern mine wastes, due to the lower efficiency of ore processing in the past. Although the knowledge of processing has significantly improved, there are still some areas in the processing sector that could be improved. Most previous studies have focused on the bulk analysis of mine wastes, without a detailed analysis of important characteristics, such as mineral texture, associations, liberation and locking. Recent studies focus on detailed mineralogical analysis, in order to more accurately assess the availability of the metals within the potential material for metal extraction. The present study investigates the geochemical and mineralogical characteristics of different mine and metallurgical waste material from a tailings pond in Plombières (East Belgium). The tailings pond covers a minimum surface area of 8000 m2, comprising 4 main types of material.  Ore microscopy, X-ray fluorescence (XRF), quantitative X-ray powder diffraction (XRD), scanning electron microscope (SEM) based Mineral Liberation Analysis (MLA) and electron microprobe (EPMA) were used to identify and characterise Pb and Zn phases within the material. XRF analysis shows that the mine wastes dominantly consist of SiO2, Al2O3 and Fe2O3, while the content of Zn and Pb varies from 51 ppm to 24 wt % and 10 ppm to 10.1 wt %, respectively. The mineralogy of the mine waste is characterised by quartz, amorphous phases and phyllosilicates, with minor amounts of Fe-oxide, Pb- and Zn-bearing minerals. Based on the processing of the ore, the amorphous phase is present as pyrometallurgical slag.  Mineral- to element- conversion shows a lack of Pb and Zn content. MLA and EPMA analysis confirm that the missing Pb is distributed between Pb- droplets within the slags and in the amorphous structure of the slags. Additionally, the analyses reveal that zinc is also dominantly located within the slags.
A Comparison of Six Transport Models of the MADE-1 Experiment Implemented with Different Types of Hydraulic Data
Authors: Zech Alraune , Attinger Sabine , Bellin Alberto , Cvetkovic Vladimir , Dagan Gedeon , Dentz Marco , Dietrich Peter , Fiori Aldo , Teutsch Georg
Published: March 2021

Six conceptually different transport models are applied to the MADE-1 field tracer experiement as a first major attempt for model comparison. The objective was to show that complex mass distributions in heterogeneous aquifers can be predicted without calibration of transport parameters - solely making use of structural and flow data.

The models differ in their conceptualization of the heterogeneous aquifer structure, computational complexity, and use of conductivity data obtained from various observation methods (Direct Push Injection Logging - DPIL, Grain Size Analysis, Pumping Tests and Flowmeter). They agree in the underlying physical transport processes, none of them considering mass transfer. Predictive capability is assessed by comparing results to observed longitudinal mass distributions of the MADE-1 experiment. We deal with data uncertainty indicated by decreasing rates of recovered mass by focusing the comparison on measures, such as peak location, position and shape of bulk mass and leading tail, and we do not normalize observation data.

Comparison of models reveals that the predictions of the solute plume agree reasonably well with observations if the models are underlined by a few parameters of close values: mean velocity, a parameter reflecting log-conductivity variability and a horizontal length scale related to conductivity spatial correlation. The robustness of the results implies that conservative transport models with appropriate conductivity upscaling strategies of various observation data provide reasonable predictions of plumes longitudinal mass distribution as long as key features are taken into account.
Comparison between polar motion excitation functions estimated from recent geophysical models and observations
Authors: Wińska Małgorzata , Śliwińska Justyna , Nastula Jolanta
Published: March 2021

Continental hydrological loading by land water, snow, and ice is a process that influences the Earth’s inertia tensor and is very important for full understanding of the excitation of polar motion. In this study, the hydrological contribution to decadal, inter-annual and multi-annual suppress polar motion derived from different GRACE (Gravity Recovery and Climate Experiment) solutions as well as from SLR (Satellite Laser Ranging) and some climate models from CMIP6 project data is discussed here.

The main aim of this study is to show the influence of different representations of hydrological angular momentum (HAM) coming from different GRACE (mas concentration solutions - mascons, Terrestrial Water Storage changes, and Stokes Coefficients), SLR, and climate models solutions on agreement between Geodetic Angular Momentum (GAM) and geophysical excitations of polar motion been a sum of Atmospheric, Oceanic and Hydrological Angular Momentum (AAM+OAM+HAM) in different spectral bands.

To do that, the geodetic and geophysical excitation functions are transformed into time-scale domain using the discrete wavelet transform based on the Complex Morlet wavelet functions. Next, the time series (GAM vs. geophysical ones) are compared in terms of semblance filtering, on the basis of their phase, as a function of frequency, and amplitude information of their cross-wavelet power.

Here, we would like to present the consistency between full polar motion excitations and geophysical fluids,  that are the sum of AAM  (pressure + wind), OAM  (bottom pressure +  currents), and HAM contributions. This analysis could let us indicate, which hydrological representation of different HAM solutions cause the biggest errors in the geodetic budget.
Autonomously observing coupled Arctic processes year-round: the Distributed Network of ice-tethered buoys during MOSAiC
Authors: Rabe Benjamin ,   Team MOSAiC Distributed Network
Published: March 2021

The Arctic Ocean is a region with unique physical processes coupling the atmosphere, sea-ice and ocean. Biogeochemical and ecosystem processes feedback with this physical system not only on a regional scale but also locally around each ice floe. Capturing these processes, both vertically and horizontally from the mesoscale to turbulence scales is essential to understand the Arctic system and to improve model simulations of this region and global climate.  

The MOSAiC Distributed Network (DN) of autonomous, ice-tethered measurement systems recorded a full seasonal cycle of atmospheric, surface, sea ice and snow, and oceanic conditions. Physical and biological variables were measured throughout the whole drift of the original MOSAiC ice floe with the icebreaker Polarstern (Central Observatory, CO) from north of Laptev Sea to Fram Strait, covering the seasons from mid-autumn 2019 to mid-summer 2020. In addition, a subset of ice-tethered buoys observed the freeze-up in the central Arctic around the second CO, after the relocation of the ice camp in late summer 2020, and even beyond the drift of Polarstern. These observations form a variety of three-dimensional datasets valuable for analyses across the spectrum of research foci covered by MOSAiC.  

We will present the scientific concept of the DN in the context of other MOSAiC observations, and show the success and preliminary scientific results from a whole year of autonomous observations.  
Assessment of groundwater contamination by chlorpyrifos using the PWC model in Valencia Region (Spain)
Authors: Pérez Indoval Ricardo , Rodrigo-Ilarri Javier , Cassiraga Eduardo
Published: March 2021

Chlorpyrifos is commoly used as an pesticide to control weeds and prevent nondesirable grow of algae, fungi and bacteria in many agricultural applications. Despite its highly negative effects on human health, environmental modeling of this kind of pesticide in the groundwater is not commonly done in real situations. Predicting the fate of pesticides released into the natural environment is necessary to anticipate and minimize adverse effects both at close and long distances from the contamination source. A number of models have been developed to predict the behavior, mobility, and persistence of pesticides. These models should account for key hydrological and agricultural processes, such as crop growth, pesticide application patterns, transformation processes and field management practices.

This work shows results obtained by the Pesticide Water Calculator (PWC) model to simulate the behavior of chlorpyrifos. PWC model is used as a standard pesticide simulation model in USA and in this work it has been used to  simulate the fate and transport of chlorpyrifos in the unsaturated zone of the aquifer. The model uses a whole set of parameters to solve a modified version of the mass transport equation considering the combined effect of advection, dispersion and reactive transport processes. PWC is used to estimate the daily concentrations of chlorpyrifos in the Buñol-Cheste aquifer in Valencia Region(Spain).

A whole set of simulation scenarios have been designed to perform a parameter sensitivity analysis. Results of the PWC model obtained in this study represents a crucial first step towards the development of a pesticide risk assessment in Valencia Region. Results show that numerical simulation is a valid tool for the analysis and prediction of the fate  and transport of pesticides in the groundwater.
Estimation of water stress in olive orchards through remote sensing data analysis
Authors: Atencia Luz Karime , Gómez del Campo María , Camacho Gema , Hueso Antonio , Tarquis Ana M.
Published: March 2021

Olive is the main fruit tree in Spain representing 50% of the fruit trees surface, around 2,751,255 ha. Due to its adaptation to arid conditions and the scarcity of water, regulated deficit irrigation (RDI) strategy is normally applied in traditional olive orchards and recently to high density orchards. The application of RDI is one of the most important technique used in the olive hedgerow orchard. An investigation of the detection of water stress in nonhomogeneous olive tree canopies such as orchards using remote sensing imagery is presented.

In 2018 and 2019 seasons, data on stem water potential were collected to characterize tree water state in a hedgerow olive orchard cv. Arbequina located in Chozas de Canales (Toledo). Close to the measurement’s dates, remote sensing images with spectral and thermal sensors were acquired. Several vegetation indexes (VI) using both or one type of sensors were estimated from the areas selected that correspond to the olive crown avoiding the canopy shadows.

Nonparametric statistical tests between the VIs and the stem water potential were carried out to reveal the most significant correlation. The results will be discussing in the context of robustness and sensitivity between both data sets at different phenological olive state.

ACKNOWLODGEMENTS

Financial support provided by the Spanish Research Agency co-financed with European Union FEDER funds (AEI/FEDER, UE, AGL2016-77282-C3-2R project) and Comunidad de Madrid through calls for grants for the completion of Industrial Doctorates, is greatly appreciated.