bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of radio occultation data to determine atmospheric profiles and associated uncertainties 
Authors: Petricca Flavio , Cascioli Gael , Genova Antonio
Published: March 2021

The analysis of atmospheric radio occultations enables an in-depth investigation of planetary ionosphere and neutral atmospheres, by measuring the radio frequency shift that affects a signal propagating through the medium. A precise characterization of the atmospheric layers requires a thorough processing of the radio tracking data to estimate the thermodynamic properties of the atmosphere and their related uncertainties.

A standard procedure to process radio occultation data requires a preliminary knowledge of the spacecraft trajectory. In this work, we present a technique to retrieve refractivity, density, pressure, and temperature profiles with their associated uncertainties through the analysis of raw radio tracking data occulted by the atmosphere. By integrating the algorithm for radio occultation processing with a Precise Orbit Determination (POD) software, an enhanced reconstruction of the spacecraft trajectory is obtained to recover the frequency shift due to the medium refraction. The resulting radio signal is then processed to yield information regarding atmospheric properties. A Monte Carlo simulation algorithm is also included to provide the formal uncertainties of the estimated parameters.

We applied this technique to radio occultation profiles of the NASA mission Mars Reconnaissance Orbiter (MRO). To validate the method, our estimated atmospheric profiles are compared to the numerical predictions of the Mars Global Reference Atmospheric Model (GRAM) and the Mars Climate Database (MCD).
Assessing the impact of land use management on the hydrodynamic behavior of vegetated water bodies colonized by riparian weed species 
Authors: Crimaldi Mariano , Lama Giuseppe Francesco Cesare
Published: March 2021

The aim of this study is the assessment of the effect of riparian vegetation management practices on the hydrodynamic behaviour of vegetated water bodies colonized by riparian weed species. The present study was carried out by calibrating the most suitable literature models on flow resistance of vegetated flows, by considering different riparian vegetation management scenarios. The key dimensional features of the examined riparian vegetation elements were estimated by comparing the outcomes of the digital processing of remote sensing and proximity sensors extremely widespread in both agricultural and forestry studies and applications. The main remarks of this study well demonstrated that the knowledge of the hydraulic and hydrological proprieties of vegetated flows at field scale is sensibly affected by the uncertainties in the measurements of riparian vegetation biomass and water quality, differently from experimental analyses conducted in dedicated flumes in the laboratory performed in standard environment conditions.
Long-term recordings at the FSU Jena Geodynamic Observatory Moxa (Thuringia, central Germany)
Authors: Kukowski Nina , Stolz Ronny , Scholtes Theo , Schwarze Cornelius , Goepel Andreas
Published: March 2021

The remote location of the Geodynamic Observatory Moxa of Friedrich-Schiller University Jena, about 30 km south of Jena in the Thuringian slate mountains, results in very low ambient noise and thus very good conditions for long-term geophysical observations, which are further improved, as many sensors are installed in the subsurface in galleries or in boreholes.

So far, the focus of Moxa observatory has been on observing transients signals of deformation and fluid movements in the subsurface. This is accomplished by sensors like a superconducting gravimeter CD-034, three laser strain meters measuring nano-strain along three galleries in north-south, east-west and NW-SE directions, or borehole tiltmeters. Further, information on fluid flow is gained from downhole temperature measurements employing an optical fiber. These sensors are complemented by a climate station and two shallow drill-holes, one of which has been fully cored, which in addition to the temperature times series provide information on water level and rock physical properties. Near surface geophysical profiling using e.g. electrical resistivity tomography has led to a good knowledge of the structurally complex subsurface of the observatory.

Recently, a node for the Global Network of Optical Magnetometers for Exotic physics (GNOME) has been installed in the temperature-stabilized room at Moxa observatory close to the superconducting gravimeter. The GNOME is a world-spanning collaboration employing optically pumped magneto­meters (OPM) to search for space-time correlated transient signatures heralding exotic physics beyond the Standard Model. GNOME is sensitive to prominent classes of dark-matter scenarios, e.g., axion or axion-like particles forming macroscopic structures in the Universe. The installation in close vicinity to the superconducting gravimeter ensures well-controlled and -monitored ambient conditions such as temperature, air pressure and especially vibrations, allowing improved vetoing of false-positive detection events in the Moxa GNOME node.

Here, we focus on introducing Moxa Observatory’s sensor systems with an emphasis of actual sensor configurations and further on highlighting how various information on fluid flow coming from the specific sensors lead to an improved understanding of the direction and magnitude of subsurface fluid flow.
Alfvénic versus non-Alfvénic turbulence in the inner heliosphere as observed by Parker Solar Probe
Authors: Velli Marco , Shi Chen , Panasenco Olga , Tenerani Anna , Reville Victor , Team the PSP*
Published: March 2021

Parker Solar Probe (PSP) measures the magnetic field and plasma parameters of the solar wind at unprecedentedly close distances to the Sun, providing a great opportunity to study the early-stage evolution of magnetohydrodynamic (MHD) turbulence in the solar wind. Here we use PSP data to explore the nature of solar wind turbulence focusing on the Alfvénic character and power spectra of the fluctuations and their dependence on heliocentric distance and context (i.e., large-scale solar wind properties), aiming to understand the role that different effects such as source properties, solar wind expansion, and stream interaction might play in determining the turbulent state. We carried out a statistical survey of the data from the first five orbits of PSP with a focus on how the fluctuation properties at the large MHD scales vary with different solar wind streams and the distance from the Sun. A more in-depth analysis from several selected periods is also presented. Our results show that as fluctuations are transported outward by the solar wind, the magnetic field spectrum steepens while the shape of the velocity spectrum remains unchanged. The steepening process is controlled by the age of the turbulence, which is determined by the wind speed together with the radial distance. Statistically, faster solar wind has higher Alfvénicity with a more dominant outward propagating wave component and more balanced magnetic and kinetic energies. The outward wave dominance gradually weakens with radial distance, while the excess of magnetic energy is found to be stronger as we move closer toward the Sun. We show that the turbulence properties can significantly vary from stream to stream even if these streams are of a similar speed, indicating very different origins of these streams. Especially, the slow wind that originates near the polar coronal holes has much lower Alfvénicity compared with the slow wind that originates from the active regions and pseudostreamers. We show that structures such as the heliospheric current sheet and wind stream velocity shears can play an important role in modifying the properties of the turbulence.

*The PSP Team: Stuart D.Bale,  Justin Kasper, Kelly Korreck, J. W. Bonnell, Thierry Dudok de Wit, Keith Goetz, Peter R. Harvey, Robert J. MacDowall, David Malaspina, Marc Pulupa, Anthony W.Case, Davin Larson,  Jenny Verniero, Roberto Livi, Michael Stevens, PhyllisWhittlesey, Milan Maksimovic, and Michel Moncuquet
Dual-carbon isotopic characterization of carbonaceous aerosol reveals different primary and secondary sources in Beijing and Xi’an during severe haze events
Authors: Ni Haiyan , Huang Ru-Jin , Dusek Ulrike
Published: March 2021

To mitigate haze pollution in China, a better understanding of the sources of carbonaceous aerosols is required due to the complexity in multiple emissions and atmospheric processes. Here we combined the analysis of radiocarbon and the stable isotope 13C to investigate the sources and formation of carbonaceous aerosols collected in two Chinese megacities (Beijing and Xi’an) during severe haze events of “red alarm” level from December 2016 to January 2017. The haze periods with daily PM2.5 concentrations as high as ~400 µg m-3 were compared to subsequent clean periods (i.e., PM2.5 < median concentrations during the winter 2016/2017), with PM2.5 concentrationsbelow 100 µg m-3 in Xi’an and below 20 µg m-3 in Beijing. In Xi’an, liquid fossil fuel combustion was the dominant source of elemental carbon (EC; 44%–57%), followed by biomass burning (25%–29%) and coal combustion (17%–29%). In Beijing, coal combustion contributed 45%–61% of EC and biomass burning (17%–24%) and liquid fossil fuel combustion (22%–33%) contributed less. Non-fossil sources contributed 51%–56% of organic carbon (OC) in Xi’an and fossil sources contributed 63%–69% of OC in Beijing. Secondary OC (SOC) was largely contributed by non-fossil sources in Xi’an (56 ± 6%) and by fossil sources in Beijing (75 ± 10%), especially during haze periods. The fossil vs. non-fossil contributions to OC and EC did not change drastically during haze events in both Xi’an and Beijing. However, compared to clean periods, the contribution of coal combustion to EC during haze periods increased in Xi’an and decreased in Beijing. During clean periods, primary OC from biomass burning and fossil sources constituted ~70% of OC in Xi’an and ~53% of OC in Beijing. From clean to haze periods, the contribution of SOC to total OC increased in Xi’an, but decreased in Beijing, suggesting that contribution of secondary organic aerosol formation to increased OC during haze periods was more efficient in Xi’an than in Beijing. In Beijing, the high SOC fraction in total OC during clean periods was mainly due to elevated contribution from non-fossil SOC. In Xi’an, a slight day-night difference was observed during the clean period, with enhanced fossil contributions to OC and EC during the day. This day-night difference was negligible during severe haze periods, likely due to enhanced accumulation of pollutants under stagnant weather conditions.
Elucidating climatic controls of polynomial trends in interannual variations of northern ecosystem productivities
Authors: Zhang Wenxin , Jin Hongxiao , Jamali Sadegh , Duan Zheng , Wu Mousong , Sun Huaiwei , Ran Youhua
Published: March 2021

Rapid warming in northern high latitudes during the past two decades may have profound impacts on the structures and functioning of ecosystems. Understanding how ecosystems respond to climatic change is crucial for the prediction of climate-induced changes in plant phenology and productivity. Here we investigate spatial patterns of polynomial trends in ecosystem productivity for northern (> 30 °N) biomes and their relationships with climatic drivers during 2000–2018. Based on a moderate resolution (0.05°) of satellite data and climate observations, we quantify polynomial trend types and change rates of ecosystem productivities using plant phenology index (PPI), a proxy of gross primary productivity (GPP), and a polynomial trend identification scheme (Polytrend). We find the yearly-integrated PPI (PPIINT) shows a high degree of agreement with an OCO-2-based solar‐induced chlorophyll fluorescence GPP product (GOSIF-GPP) for distinct spatial patterns of trend types of ecosystem productivities. The averaged slope for linear trends of GPP is found positive across all the biomes, among which deciduous broadleaved and evergreen needle-leaved forests show the highest and lowest rates respectively. The evergreen needle-leaved forests, low shrub, and permanent wetland show linear trends in PPIINT over more than 50% of the covered area and permanent wetland also shows a large fraction of the area with the quadratic and cubic trends. Spatial patterns of linear trends for growing season sum of temperature, precipitation, and photosynthetic active radiation have been quantified. Based on the partial correlations between PPIINT and climate drivers, we found that there is a consistent shift of dominant drivers from temperature or radiation to precipitation across all the biomes except the permeant wetland when the trend type of ecosystem productivity changes from linear to non-linear. This may imply precipitation changes in recent years may determine the linear or non-linear responses of ecosystem productivity to climate change. Our results highlight the importance of understanding how changes in climatic drivers may affect the overall responses of ecosystems productivity. Our findings will facilitate the sustainable management of ecosystems accounting for the resilience of ecosystem productivity and phenology to future climate change.
Raman estimates of the thermal effect on tree trunks in the Siberian Traps lavas and volcaniclastics
Authors: Polozov Alexander G. , Planke Sverre , Millett John A. , Zastrozhnov Dmitrii A. , Ponkratov Kirill V. , Jerram Dougal A. , Svensen Henrik H.
Published: March 2021

Tree trunks in lava flows and volcaniclastics of the Siberian Traps witness volcanic activity's violent and rapid onset. Carbonized and petrified trees preserve the peak metamorphic temperatures, which can be estimated using Raman spectroscopy. We have conducted a Raman study of the tree trunks and wooden fragments trapped in the Siberian Traps volcaniclastics and lavas on the Tunguska basin's northwestern region (Norilsk area). The first sample set was taken from volcaniclastic rocks of the Kureika River. The second sample set was collected from the lowermost lava flow of Ivakinskaya Formation that erupted directly on the end-Permian boggy surface (Tunguska Group of Carboniferous-Permian age) and from the coal-bearing inter lava seam at Red Rocks outcrop near Talnakh. The third sample set was taken from in the basal part of the Ivakinskaya Fm lowermost lava flow erupted in a shallow water basin with pillow basalt formation (Ore Brook near Norilsk). The fourth sample set was taken from an open coal pit with shallow dolerites intruded into the late Permian part of the Tunguska Group (near Kajerkan). We analyzed carbonized wood with a Renishaw InVia Qontor with 532 nm laser and processed all spectra with Henry et al. (2018) recommendations. The peak metamorphic temperature was calculated from Deldicque et al. (2016) equation 2. The tree trunks of the first sample set (Kureika River volcaniclastics) have a narrow median temperature range (430-468oC with one sample of 612oC). The second sample set from tree trunks in lavas and the coal-bearing inter lava seam (Red Rocks near Talnakh) ranges between 343-658oC and 742-764oC. The third sample set from pillow basalt at the basal part of Ivakinskaya Fm. (Ore Brook near Norilsk) also has a narrow temperature range (503-535oC with one sample of 650oC). The last sample set from the open coal pit (near Kajerkan) has a wide median temperature range (388-632oC).

We explain these variations by different styles of the Siberian Traps eruption. At the Kureika River, the end-Permian forest was buried and carbonized by tephra. At the Talnakh area, lava flow erupted on the boggy surface, whereas in the Norilsk area, the lava flow erupted into the freshwater basin.

 

Henry, D.G. et al. (2018). Int. J Coal Geol, 191: 135-151

Deldicque, D. et al. (2016). Carbon, 102: 319-329
High Resolution Paleoclimate Simulations with the COSMO-CLM Model in the Eastern Mediterranean and Middle East
Authors: Hartmann Eva , Zhang Mingyue , Xoplaki Elena , Wagner Sebastian
Published: March 2021

The Eastern Mediterranean and Middle East region is influenced by multiple large-scale atmospheric circulation patterns including the Indian Summer Monsoon the North Atlantic Oscillation (NAO), the East Atlantic / Western Russia and Scandinavian patterns. The area offers a broad spectrum, both in time and space, of long high-quality instrumental time series, documentary information and natural archives. Yet, recent reviews revealed that paleoclimate modelling with low horizontal resolution cannot fully help to understand the interactions of the multiple atmospheric patterns, the Mediterranean SSTs and connect potential climate impacts that may trigger or contribute to major social-historical events. Thus, there is a need to integrate high-resolution regional climate modelling into paleo applications. Furthermore, such integration will close the gap between the coarse resolution of climate models and the regional to local scale that is covered by the proxy and historical evidence and will enable a better data-model comparison. We use the regional climate model COSMO-CLM (CCLM) in an adjusted (orbital, solar and volcanic forcing, greenhouse gas concentrations and land-use changes) paleoclimate version. Simulations are performed with 0.44° and 0.11° spatial resolution on a domain including the Eastern Mediterranean and the Middle East in time slices of the past 2000 years. Simulations of the present (1979-2019) with this paleoclimate version of CCLM forced by ERA-Interim reanalysis data have shown promising results compared to observational and reanalysis data sets. The mean annual cycles of precipitation and temperature of the Mediterranean are correctly shown with high temperatures and low precipitation during the summer months and lower temperatures and higher precipitation during the winter months. Additionally, the effect of climate change is simulated with increasing temperatures during the last 40 years. Simulations of the present (1979-2019) and past periods (525-575 CE and 1220-1290 CE) forced by the MPI-ESM-LR ‘past2k’ simulations performed under the CMIP6 protocol will be performed at the next step and first results will be shown in the frame of this conference. The periods are chosen because of high volcanic activity and to study the volcanic influence on climate. Those results are going to be used to link historical events with the regional climate and contribute to a better understanding of the indirect and complex association between climate and society.
A hybrid rainfall prediction model for Tunisian agriculture regions based on OSM data, Voronoi spatial analysis and Long Short Term Memory deep learning
Authors: Ben Rhaiem Mohamed Amine , Ben Hassine Abderrahmane , Ouertani Amine , Riadh Farah Imed
Published: March 2021

The agriculture sector in Tunisia plays a vital role in the Tunisian economy with 6% of the country's exports earning, 12.6% of GDP and almost one
quarter of the country's labor force. However, Tunisian agriculture is still increasingly exposed to a variety of vulnerabilities and uncertainties including in particular the climate variability such as drought and floods. In fact, Rainfall quantity and its geographic distribution are the main drivers of water productivity and agriculture production and a predominant key factor in the overall agriculture hazard risk management processes. This paper uses the daily open rainfall data from the national observatory of Tunisian agriculture (ONAGRI) to develop an ETL (Extract,Transform and load) tool to automatically spatialize and load the historical data into a big data platform by continuously incrementing the new daily disseminated records. In addition, this paper applies the Voronoi spatial analysis model to estimate rainfall measures for the newly added spatial units using VGI data from OSM world mapping project. Then, based on these spatial estimations, the paper examines the feasibility of applying ARIMA (Auto Regressive Integrated Moving Average) for time series forecasting by comparing it with deep learning methods ANN (Arti cial Neural Network) and LSTM (Long Short Term Memory) in order to predict the rainfall values corresponding to particular agriculture area belonging to a Tunisian region. Our experimental results showed that prediction accuracy increased with LSTM model comparing to the other models for the rainfall time series forecasting embedded now with geographic location.
Determination of anthropogenic contamination by 137Cs, 240Pu/239Pu and 235U/238U in lichens and mosses from Russian Arctic areas 
Authors: Salminen-Paatero Susanna , Dutheil Paul , Sundström Timo , Rodushkin Ilia , Paatero Jussi
Published: March 2021

Lichen and moss samples were collected from Russian Arctic areas (Kola Peninsula, Franz Josef Land and few other locations) in the 1990s. In 2020, 137Cs was determined by HPGe gamma spectrometry from these samples after which isotopes of Pu and U were radiochemically separated from the samples. Mass ratios 240Pu/239Pu and 235U/238U were determined by ICP-MS for utilizing the characteristic isotopic fingerprints of different nuclear events. The aim of the work was to survey radioactive contamination sources in terrestrial environment in Russian Arctic regions, which have not yet been completely explored in respect to anthropogenic isotopes and their origin in the environment.
Coronal loops in a box: 3D models of their internal structure, dynamics and heating
Authors: Breu Cosima , Peter Hardi , Cameron Robert , Solanki Sami , Chitta Pradeep , Przybylski Damien
Published: March 2021

The corona of the Sun, and probably also of other stars, is built up by loops defined through the magnetic field. They vividly appear in solar observations in the extreme UV and X-rays. High-resolution observations show individual strands with diameters down to a few 100 km, and so far it remains open what defines these strands, in particular their width, and where the energy to heat them is generated.

The aim of our study is to understand how the magnetic field couples the different layers of the solar atmosphere, how the energy generated by magnetoconvection is transported into the upper atmosphere and dissipated, and how this process determines the scales of observed bright strands in the loop.

To this end, we conduct 3D resistive MHD simulations with the MURaM code. We include the effects of heat conduction, radiative transfer and optically thin radiative losses.
We study an isolated coronal loop that is rooted with both footpoints in a shallow convection zone layer. To properly resolve the internal structure of the loop while limiting the size of the computational box, the coronal loop is modelled as a straightened magnetic flux tube. By including part of the convection zone, we drive the evolution of the corona self-consistently by magnetoconvection.

We find that the energy injected into the loop is generated by internal coherent motions within strong magnetic elements. 
The resulting Poynting flux is channelled into the loop in vortex tubes forming a magnetic connection between the photosphere and corona, where it is dissipated and heats the upper atmosphere.

The coronal emission as it would be observed in solar extreme UV or X-ray observations, e.g. with AIA or XRT, shows transient bright strands.
The widths of these strands are consistent with observations. From our model we find that the width of the strands is governed by the size of the individual photospheric magnetic field concentrations where the field lines through these strands are rooted. Essentially, each coronal strand is mainly rooted in a single magnetic patch in the photosphere, and the energy to heat the strand is generated by internal motions within this magnetic concentration.

With this model we can build a coherent picture of how energy and matter are transported into the upper solar atmosphere and how these processes structure the interior of coronal loops.
Chemical pretreatment effects on grain size results of clastic sediments and soils
Authors: Gresina Fruzsina , Szalai Zoltán , Varga György
Published: March 2021

Determining the particle size is a current problem in many earth science sub-disciplines. Particle size distributions of sediments provide insight into the physicochemical environment, transport, accumulation and accumulation of particle formation, and post-deposition transformation processes. Therefore, granulometric proxies are widely used in paleoclimate research and many soil properties depend on their particle size distribution. Several studies are available comparing different laser diffraction devices, optical theories, and optical settings. Ignoring limitations of laser diffraction technique can result in poorly comparable granulometric data sets, however, inadequate chemical pretreatment procedures are also limiting factors, which are often overlooked. In this study, we examined different sediment types from various geomorphological environments from the Carpathian Basin: lake, eolian, fluvial sediments and paleosols. Our aim is to review and create a reliable methodology for laser diffraction particle size analysis and optical particle shape investigations. The widely used pretreatment methods (total of 13) were compared. The results showed that the samples with different textural parameters were differently affected by the preparation procedures. Compared to the silty textured loess and paleosol samples, applied techniques did not cause substantial changes of results of sandy materials, although the duration and the applied amount of the reagent had some impact on the grain size data.  Using cluster analysis, the various pretreatment methods could be separated from each other proving that these procedures are able to create substantially different grain size datasets. Shape parameters of the particles were also modified by the pretreatment methods, significant changes could be observed in the circularity, convexity characteristics. The study is supported by the ÚNKP-19-3 New National Excellence Program of the Ministry for Innovation and Technology. The support of the National Research, Development, and Innovation Office (projects NKFIH KH130337 and K120620) is gratefully acknowledged.
Loss of climatic suitability for durum wheat production
Authors: Ceglar Andrej , Toreti Andrea , Zampieri Matteo , Royo Conxita
Published: March 2021

Durum wheat (Triticum durum Desf.) is a minor cereal crop of key importance for making pasta, couscous, puddings, bread, and many other traditional foods, due to its physical and chemical characteristics. Durum wheat currently represents around 8% of the total wheat crop production, with the main cultivation region being concentrated in few suitable areas such as the Mediterranean Basin, the North American Great Plains, and the former USSR. The global demand for high-quality food made of durum wheat has been increasing, which poses a challenge in the face of climate change. The major share of durum wheat production is currently located in semi-arid climates, where the risk of climate extremes such as drought and heat stress will likely substantially increase in the future. 

We develop a global climate suitability model for durum wheat growth based on Support Vector Machines. We use CMIP6 data to assess the impact of climate change on future suitability for growing durum wheat globally. The total share of global arable land, climatically suitable for growing rainfed durum wheat, currently represents roughly 13% of the global arable land. However, climate change may decrease this suitable area of 19% by mid-century and of 48% by the end of the century, considering also the gain of suitable land areas, where durum wheat is not cultivated today. This net loss of suitable areas requires the development and the future adoption of effective and sustainable strategies to stabilize production and adapt the entire food supply chain.
Diversity, Equity, and Inclusion (DEI) at AGU:  New Leadership Commitments and Progress Under an Updated Strategic Plan  
Authors: Williams Billy , Fraiser Margaret , White Lisa , Asher Pranoti , Hanson Brooks
Published: March 2021

The American Geophysical Union (AGU), a global scientific society of >60,000 members, has a series of initiatives underway to address issues of diversity, equity, and inclusion in the Earth and space sciences, including the well-known issues of harassment and its impact on women scientists, and the closely related issues of systemic racism, sexism, ableism, discrimination against LGBTQ community, and their related intersectional issues. Building on its earlier work of establishing an updated AGU Ethics Policy which defines harassment and discrimination as scientific misconduct, AGU has taken additional significant steps over the past 12 months to further advance Diversity, Equity and Inclusion (DEI) practices— including work lead by the AGU Diversity and Inclusion Advisory Committee to launch a public facing AGU D&I dashboard, steps under the updated AGU Strategic plan to provide additional resources for supporting a more equitable and inclusive culture, and work and commitments by AGU leadership to address systemic racism through its “Eight Deliberate Steps.”  This presentation will highlight new AGU DEI-related initiatives most recently underway, including the role of partnerships in helping to achieve the broader DEI culture change objectives, and the associated work across AGU Meetings, Publications, and Honors. Progress to date on these and other emerging new AGU Justice Equity Diversity and Inclusion (JEDI)-related resources and partnership initiatives, including metrics to track the impact of these changes, will be discussed.
Aerosol and Cloud Changes during the Corona Lockdown in 2020 – First highlights from the BLUESKY campaign
Authors: Voigt Christiane , Lelieveld Jos , Schlager Hans , Schneider Johannes , Sauer Daniel , Meerkötter Ralf , Pöhlker Mira , Bugliaro Luca , Curtius Joachim , Erbertseder Thilo , Hahn Valerian , Jöckel Patrick , Li Qiang , Marsing Andreas , Mertens Mariano , Pöhlker Christopher , Pöschl Ulrich , Pozzer Andrea , Tomsche Laura , Schumann Ulrich
Published: March 2021

Worldwide regulations to control the COVID-19 pandemic caused significant reductions in ground and airborne transportation in spring 2020. This unprecedented situation provided the unique opportunity to directly measure the less perturbed atmosphere, notably near the tropopause, and derive the effects of anthropogenic emissions on atmospheric composition, aerosol, clouds and climate. These changes were investigated during the BLUESKY experiment by the two research aircraft HALO and the DLR Falcon, satellite observations and models. From 16 May to 9 June 2020, the two research aircraft performed 20 flights over Europe and the North Atlantic. Profiles of trace species were measured with an advanced in-situ trace gas, aerosol and cloud payload from the boundary layer to 14 km altitude. Here, we present an overview and selected highlights of the BLUESKY experiment. Continental aerosol profiles show significant reductions in aerosol mass in the boundary layer. The reduced aerosol optical thickness above Germany has also been detected by MODIS and its impact on the colour of the sky is investigated. A specific focus was the detection of aerosol and cirrus changes caused by up to 90% reductions in air traffic. We find reductions in fine mode aerosol in the UTLS at various levels compared to CARIBIC data. In addition, we derive reductions in contrail and cirrus cover using passive and active remote sensing from satellite combined with cloud modeling. The comprehensive data set acquired during the 2020 lockdown period allows better understanding and constraining the anthropogenic influence on the composition of the atmosphere and its impacts on air quality and climate.
The representativeness of ground-based air quality monitoring stations: observation and recommendation from Indian cities 
Authors: Roy Arindam , Takahama Satoshi , Nenes Athanasios , Sharma Sumit , Goel Anju
Published: March 2021

It is well established that the high level of particulate matter is a leading cause of premature mortality and disease worldwide and especially in South Asia (Global Burden of Disease Study, 2019). The ground-based air quality (AQ) monitoring stations are used to calculate economic loss, premature mortality and validate the conversed PM2.5 concentration from satellite-based Aerosol Optical Depth (AOD) data. Over India, 793 manual monitoring air quality (AQ) monitoring stations and 307 automated AQ monitoring station are presently operating under the aegis of National Air Quality Monitoring Programme and Central Pollution Control Board respectively. However, studies addressing the spatial representativeness of the data generated from the AQ monitoring stations over India are very limited and therefore, it is unclear that whether the existing stations are sufficient to reflect the average ambient AQ over different Indian cities. 

The present study intends to classify the existing AQ monitoring stations on the basis of spatial representativeness and derive a general conceptual framework for commissioning representative AQ monitoring sites for Indian cities. The methodology involves analysis of land use, populations and air quality data for the existing air quality stations in million plus Indian cities. A case study was conducted for Pune (18.5° N, 73.8° E), a western Indian metro city with 3.15 million population (Census, 2011). Using the night-time light data and high resolution PM2.5, population exposure hotspots over Pune city were identified. It was observed that not only at the midst of the municipal area, population exposure hotspots can be identified at the peripheral region of PMC/PNMC which certainly signify the role of rapid developmental activity and urban agglomeration over Pune city. The existing air quality monitoring sites are located majorly in the pollution hotspots in the city center region and therefore installing AQ monitoring stations (co-located  with weather station) at the rapidly developing parts of the city is highly recommended. The present land use pattern and the location of existing monitoring sites suggests lack of urban background monitoring stations which indicates the gap of knowledge in monitoring the average air quality responsible of long-term health effect over Pune. The prevalence of AQ monitoring stations in the road junction points and near to metro construction works might overestimate the exposure estimate of the general population in the city.   
Palaeogeographic evolution and sea level changes of a tectonically active area: the case of Psatha, Alkyonides Gulf, Greece
Authors: Karkani Anna , Saitis Giannis , Tsanakas Konstantinos , Evelpidou Niki , Karymbalis Efthimios , Vassilakis Emmanuel , Drinia Hara , Batzakis Dimitrios-Vasileios
Published: March 2021

The study of environmental changes in coastal areas provide useful information for past conditions and constitute a powerful tool for accurate palaeogeographic reconstructions. Several coastal landforms are present on the coastal zone, with different response to environmental change. Coastal wetlands and lagoons are particularly sensitive to local paleoenvironmental changes and provide an excellent opportunity to reconstruct the evolution of the coastal zone evolution and the sea level changes. In this context, the aim of this work is to elucidate the coastal evolution of Psatha bay, Alkyonides Gulf, Greece, through coastal drillings and geomorphological sea level markers.

The study area is located at the eastern end of Corinth Gulf, in the Gulf of Alkyonides. Psatha is bounded by active neotectonic structures, which have been a determining factor in its development. In this work we adopt a multiproxy approach through the study of coastal drillings and beachrocks, and micro-topography constructed after photogrammetric processing of very high resolution and accuracy images acquired by several Unmanned Aerial System flights. We coupled detailed beachrock mapping, microstratigraphic analysis and luminescence dating to study beachrock outcrops found up to 1 m above the present sea-level. For the palaeoenvironmental reconstruction, multiproxy analyses were undertaken, which included sedimentological analysis of the core, paleontological analysis of macrofauna and microfauna and radiocarbon dating. The results of this work will contribute to the better understanding of a coastal site in a tectonically active area and the relative sea level changes.
Application and performance of Kestrel sensors for assessing thermal comfort in outdoor built environments
Authors: Klok Lisette , Caverzam Barbosa Erica , van Zandbrink Luc , Kluck Jeroen
Published: March 2021

In face of climate change and urbanization, the need for thermally comfortable outdoor urban spaces is increasing. In the design of the thermally comfortable urban spaces and decision making about interventions that enhance thermal comfort, scientists and professionals that work for cities use meteorological measurements and models. These measurements can be done by professional and accurate meteorological sensors, but also by simpler mobile instruments such as the easy-to-use Kestrel weather meters. In using these simple type of sensors, it is important to know what the performance of these sensors is for outdoor thermal comfort assessments and how they can be used by scientists and professionals in decision making about urban designs that enhance thermal comfort.

To answer these questions, we carried out three experiments in the summer of 2020 in Amsterdam, in which we tested the 11 Kestrel 5400 heat stress sensors and assessed the performance of this equipment for thermal comfort studies. We concluded that Kestrel sensors can be used very well for assessing differences in air temperature and PET (Physiological Equivalent Temperature) between outdoor built environments. For both air temperature and PET, the RMSE between the 11 Kestrel sensors was 0.5 °C maximum when measuring the same conditions. However, Kestrel sensors that were placed in the sun without a wind vane mounted to the equipment showed large radiation errors. In this case, temperature differences up to 3.4 °C were observed compared to Kestrels that were shaded. The effect of a higher air temperature on the PET calculation is, however, surprisingly small. A sensitivity analysis showed that an increase of 3 °C in the air temperature results in a maximal PET reduction of 0.5 °C. We concluded that Kestrel sensors can very well be used for assessing differences between air temperatures and PET between two locations and assessing the thermal effects of urban designs, but care should be taken when air temperature measurements are carried out in the sun. We always recommend using the wind vanes to deviate from high radiant input orientations for the temperature sensor, and placing the stations next to each other at the beginning and at the end of the measurements to check whether the stations actually measure the same values. Any differences can be corrected afterwards.
Vectors to ore in replacive VMS deposits of the northern Iberian Pyrite Belt: the case study of Aguas Teñidas deposit
Authors: Gisbert Guillem , Tornos Fernando , Losantos Emma , Pons Juan Manuel
Published: March 2021

Volcanogenic Massive Sulphide (VMS) deposits represent a major source of base, precious and other metals of economic and industrial importance. The Iberian Pyrite Belt (IPB) is an outstanding VMS district located in the SW Iberian Peninsula. It is arguably the largest known accumulation of sulphides on the Earth’s crust, and represents the main mining area in Spain and one of the main zones of base metal production in Europe. As in other mining areas, progressive exhaustion of the most shallow and easily accessible deposits is leading to increasingly complex exploration. In this context, the combined study of the mineral systems and the development of new exploration strategies and technologies based on geophysical methods and vectors to ore play a vital role.

Vectors to ore have the potential to detect the nearby presence of an ore deposit, and to provide information on its likely location or characteristics. But work on vectors to ore in IPB is far from systematic or complete. Previous works have focused on the study of the larger exhalative shale-hosted deposits of the southern IPB or the giant Rio Tinto deposit, but little attention has been paid to the predominantly volcanic rock hosted replacive deposits of the northern IPB, which, although generally smaller in size compared to southern deposits, typically present higher base metal concentrations.

In this work we have performed a detailed study of the main vectors to ore currently used in the exploration of VMS systems on a representative volcanic rock hosted replacive VMS deposit located in the northern IPB, the Aguas Teñidas deposit. These have included: mineralized unit identification based on whole rock geochemistry, study of the characteristics and behaviour of whole rock geochemical anomalies around the ore (e.g. alteration-related compositional changes, characteristics and extent of geochemical halos around the deposit), with definition of mineralization-related indicative elements threshold values, application of portable XRF analysis to the detection of the previous vectors, and characterization of major elements trends in mineral chemistry (muscovite, chlorite, carbonate) within and away from the mineralized system.

Data presented in this work are not only applicable to VMS exploration in the IPB, but on a broader scale they will also contribute to improve our general understating of vectors to ore in replacive-type VMS deposits.

The authors thank MATSA for providing information and access to drill-cores from Aguas Teñidas deposit. This research has been conducted within the NEXT (New Exploration Technologies) project and has received funding by the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 776804.
CubeSats deliver daily crop water use at 3 m resolution
Authors: Aragon Solorio Bruno Jose Luis , Ziliani Matteo G. , McCabe Matthew F.
Published: March 2021

Precision agriculture needs accurate information on crop water use (via evaporation) at high spatiotemporal resolutions. Conventional satellite missions have traditionally required a compromise between having high spatial resolution retrievals occasionally; or coarse resolution captures regularly. The development of CubeSats is relaxing the need for such a compromise by monitoring the Earth at high spatiotemporal resolutions. Here, we show the results of using Planet’s daily CubeSat imagery to derive evaporation at 3 m spatial resolution over three agricultural fields in Nebraska USA. Our results indicate that the derived evaporation estimates can provide accurate information on crop water use when evaluated against eddy covariance measurements (r2 of 0.86-0.89; mean absolute error between 0.06-0.08mm/h) and deliver new insights to enhance water security efforts and in-field decision making.
Forced Changes in the Arctic Freshwater Budget Emerge in the Early 21st Century 
Authors: Jahn Alexandra , Laiho Rory
Published: March 2021

Arctic liquid freshwater (FW) storage has shown a large increase over the past decades, posing the question: Is the Arctic FW budget already showing clear signs of anthropogenic climate change, or are the observed changes the result of multi-decadal variability? Using large ensemble simulations from the Community Earth System model (CESM), we show that the observed change in liquid and solid Arctic FW storage is likely already driven by the changing climate. Generally, the emergence of forced changes in Arctic FW fluxes occurs earlier for oceanic fluxes than for atmospheric or land fluxes. Nares Strait liquid FW flux is the first to show emergence outside the range of background variability in the model, with this change potentially already occurring, followed by Davis Strait. Other FW fluxes have likely started to shift but have not   yet emerged into a completely different regime. By re-sampling the model simulations, we find that the already changing nature of many FW budget terms over the short (~maximum 25 years) observational period can delay detection of shift and emergence from observations. Future emissions reductions have the potential to avoid the emergence of some FW fluxes beyond the background variability, in particular for runoff and Fram Strait solid FW export. However, under both low and high warming scenarios, all FW fluxes show changes, just not always completely outside the background variability as simulated by the CESM. Overall, this study provides an example of how large ensembles can be used to diagnose forced changes in short observational timeseries.
On the numerical study of thermohydrodynamics and biochemistry of inland water bodies
Authors: Gladskikh Daria , Mortikov Evgeny , Stepanenko Victor
Published: March 2021

The study of thermodynamic and biochemical processes of inland water objects using one- and three-dimensional RANS numerical models was carried out both for idealized water bodies and using measurements data. The need to take into account seiche oscillations to correctly reproduce the deepening of the upper mixed layer in one-dimensional (vertical) models is demonstrated. We considered the one-dimensional LAKE model [1] and the three-dimensional model [2, 3, 4] developed at the Research Computing Center of Moscow State University on the basis of a hydrodynamic code combining DNS/LES/RANS approaches for calculating geophysical turbulent flows. The three-dimensional model was supplemented by the equations for calculating biochemical substances by analogy with the one-dimensional biochemistry equations used in the LAKE model. The effect of mixing processes on the distribution of concentration of greenhouse gases, in particular, methane and oxygen, was studied.

The work was supported by grants of the RF President’s Grant for Young Scientists (MK-1867.2020.5, MD-1850.2020.5) and by the RFBR (19-05-00249, 20-05-00776). 

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2. Mortikov E.V., Glazunov A.V., Lykosov V.N. Numerical study of plane Couette flow: turbulence statistics and the structure of pressure-strain correlations // Russian Journal of Numerical Analysis and Mathematical Modelling. 2019. 34(2). P. 119-132.
3. Mortikov, E.V. Numerical simulation of the motion of an ice keel in stratified flow // Izv. Atmos. Ocean. Phys. 2016. V. 52. P. 108-115.
4. Gladskikh D.S., Stepanenko V.M., Mortikov E.V. On the influence of the horizontal dimensions of inland waters on the thickness of the upper mixed layer // Water Resourses. 2021.V. 45, 9 pages. (in press) 