bluuebunny/crossref_metadata_2025 huggingface dataset:
Four decades of radar-echo sounding: The past, present, and future of radar applications for understanding subglacial environments 
Authors: Chu Winnie
Published: March 2021

Airborne radar sounding observations have been instrumental in understanding subglacial environments and basal processes of ice sheets. Since the advent of analog radar-echo sounding (RES) system in the early 1970s, there have been tremendous innovations in both RES hardware and signal processing techniques. These technological advancements have provided high-resolution ice thickness measurements, improved detection and characterization of subglacial hydrology, as well as improved understanding of basal thermal conditions, bed roughness and geomorphology, and other processes that govern the basal boundary of the polar ice sheets. In this talk, I will provide an overview of the recent developments in radar processing approaches and system designs and highlight some of the new understanding of ice sheet subglacial processes that emerge from these breakthroughs. I will end by discussing areas where future radar applications and discoveries may be possible, including the utilization of machine learning algorithms, space-borne radar missions, and ground-based passive radar platforms to provide long-term monitoring of ice sheet subglacial environments.
Spatiotemporal change of water level in ungauged high-altitude tropical lakes: a DInSAR approach
Authors: Palomino-Ángel Sebastián , Vázquez Raúl F. , Hampel Henrietta , Anaya-Acevedo Jesús A. , Mosquera Pablo V. , Jaramillo Fernando
Published: March 2021

Spatiotemporal characteristics of physical responses of lakes to external and environmental changes are still largely unknown due to the consistent lack of monitoring of water level and corresponding changes in water storage in lakes. Understanding these changes is a fundamental step in advancing regional management of natural and anthropogenic systems that depend on the water resources of lakes. As an illustrative example, we here report a case study involving lakes of the headwater topical Andes mountain range, which, despite guaranteeing water security to millions of downstream inhabitants, still remain significantly ungauged. We present a novel evaluation of the potential of Differential Interferometric Synthetic Aperture Radar DInSAR techniques for the spatiotemporal analysis of patterns of water level change in lakes such as the ones comprising these ungauged high-altitude lake systems. Time series of Sentinel-1B data for the years 2017 and 2018 were used to generate continuous interferograms representing water level changes in twenty-four lakes of the Cajas National Park, Ecuador. The relation of these water level changes with climatic and topographical factors were analyzed to validate the methodology, and determine any patterns of change and response to climatic drivers. We found relatively high Pearson correlation coefficients between regional precipitation and water level change as estimated from the interferograms. Furthermore, we found an important negative relationship between water level change, as obtained from the DInSAR phase, and lake surface area. The study revealed a spatial trend of this correlation in terms of the altitude of the lakes at the basin scale; that is, lower correlation values were found in the headers of the basins, whilst higher correlation values were found at lower basin altitudes. The results of the present study demonstrate the potential of DInSAR techniques based on Sentinel-1 data for the monitoring of hydrologic changes in open water surfaces, and the possible validation of the DInSAR results with precipitation when gauged water level data is missing. These results are a basis to propose monitoring strategies in ungauged high-altitude lake systems in regions with similar data gauging constraints. Future work will encompass the integration of ongoing water level gauging for further validation of the herein depicted lake water level estimation approach.
Impact Assessment of Aeolus Winds on NOAA Global Forecast
Authors: Liu Hui , Garrett Kevin , Ide Kayo , Hoffman Ross , Luekens Kathrine
Published: March 2021

Recent efforts have focused on evaluation of the reprocessed Aeolus Level 2B (L2B) wind data with ESA M1 bias correction and its impact on NOAA global forecast. Aeolus wind quality especially the remaining biases vs NOAA global model background is examined. As a result, a revised bias correction taking account of noises in both Aeolus and GFS winds is implemented in the NOAA global data assimilation system to improve Aeolus wind assimilation.  In this study we will present impact from Aeolus wind on NOAA global forecast, focusing on synoptic and mesoscale scale events, e.g., tropical cyclones track and intensity in Eastern Pacific, and heavy rainfalls over the Western Coast of US.
Budget of nitrous acid (HONO) and its impacts on atmospheric oxidation capacity at an urban site in Guangzhou of China
Authors: Yu Yihang , Cheng Peng , Li Huirong , Yang Wenda , Han Baobin , Yu Xiaofang , Zhang Manman , Song Wei , Huang Zhijiong , Yuan Bin
Published: March 2021

Nitrous acid (HONO) can produce hydroxyl radicals (OH) by photolysis and plays an important role in atmospheric photochemistry. Over the years, high concentrations of HONO have been found in the Pearl River Delta region (PRD), which may be one of the reasons for the high atmospheric oxidation capacity. A comprehensive atmospheric observation was conducted at an urban site in Guangzhou from 27 September to 9 November 2018. During the period, HONO ranged from 0.02 to 4.43 ppbv with an average of 0.74±0.70 ppbv. The combustion emission ratio (HONO/NOx) of 0.9±0.4% was derived from 11 fresh plumes. The primary emission rate of HONO during night was calculated with the emission source inventory data to be between 0.04±0.02 and 0.30±0.15 ppbv/h. And the HONO produced by the homogeneous reaction of OH+NO at night was 0.26±0.08 ppbv/h, which can be seemed as secondary results from primary emission. They were both much higher than the increase rate of HONO (0.02 ppbv/h) during night. Soil emission rate of HONO at night was calculated to be 0.019±0.0003 ppbv/h. Deposition was the dominant removal process of HONO during night, and a deposition rate of at least 2.5 cm/s is required to balance the direct emissions and OH+NO reaction. Correlation analysis shows that NH3 and relative humidity (RH) may participate in the heterogeneous transformation from NO2 to HONO during night. In the daytime, the average primary emission Pemis was 0.12±0.01 ppbv/h, and the homogeneous reaction POH+NO was 0.79±0.61 ppbv/h, which was even larger than the unknown sources PUnknown (0.65±0.46 ppbv/h). The results showed that the direct and indirect contributions of primary emission to HONO are great at the site, both during daytime and nighttime. Similar to previous studies, PUnknown was suggested to be related to the photo-enhanced reaction of NO2. The mean OH production rates by photolysis of HONO and O3 were 3.7×106 cm-3·s-1 and 4.9×106 cm-3·s-1, respectively. We further studied the impact of HONO on the atmospheric oxidation by a Master Chemical Mechanism (MCM) box model. When constraining observed HONO in the model, OH and O3 increased 59% and 68.8% respectively, showing a remarkable contribution of HONO to the atmospheric oxidation of Guangzhou.

 
Vertical distribution of aerosol particles over the Russian Arctic derived from in-situ aircraft measurements: the September 2020 campaign
Authors: Arshinov Mikhail Yu. , Belan Boris , Davydov Denis , Kozlov Artem , Fofonov Alexandr
Published: March 2021

The Arctic is warming much faster than other regions of the globe. In 2020, temperature anomalies in the Russian Arctic reached unprecedented high levels. The atmospheric composition in this key region still remains insufficiently studied that makes difficult predicting future climate change.

In September 2020, an extensive aircraft campaign was conducted to document the tropospheric composition over the Russian Arctic. The Optik Tu-134 research aircraft was equipped with instruments to carry out in-situ measurements of trace gases and aerosols, as well as with a lidar for profiling of aerosol backscatter. The aircraft flew over a vast area from Arkhangelsk to Anadyr. Six measurement flights with changing altitudes from 0.2 to 9.0 m were conducted over the waters of the Barents, Kara, Laptev, East Siberian, Chukchi, and Bering Seas. The weather was unusually warm for this period of the year, surface air temperatures were above 0°C through the campaign.

Here, we present the results of in-situ measurements of the vertical distribution of aerosol number concentrations in a wide range of sizes. A modified diffusional particle sizer (DPS) consisted of the Novosibirsk-type eight-stage screen diffusion battery connected to the TSI condensation particle counter Model 3756 was used to determine the number size distribution of particles between 0.003 mm and 0.2 mm (20 size bins). Distribution of particles in the size range from 0.25 µm to 32 µm (31 size bins) was measured by means of the Grimm aerosol spectrometer Model 1.109.

The flights over Barents and Kara Seas were predominantly performed under clear sky or partly cloudy weather conditions. Number size distributions were wide representing particles of almost all aerosol fractions. When flying in the upper troposphere with a constant altitude over these seas, some cases of enhanced concentrations of nucleation and Aitken mode particles comparable to ones in the lower troposphere were recorded, suggesting in situ new particle formation was likely to be taking place via gas-to-particle conversion aloft.

East of the Kara Sea, flights were conducted under mostly cloudy conditions resulting in a lower median aerosol number concentration and narrower size distributions.

This work was supported by the Russian Foundation for Basic Research (Grant No. 19-05-50024).
The thermochemical structure of West Antarctica from multi-observable probabilistic inversion
Authors: Ben Mansour Walid , Wiens Douglas A. , Shen Weisen , Lloyd Andrew J.
Published: March 2021

The interaction between ice sheets and mantle dynamics is crucial to understanding the present-day topography in many regions (Antarctica, Patagonia, North America, Scandinavia) and recent ice mass losses on a large scale. A better knowledge of mantle rheology and the physical properties beneath these regions will improve our understanding of this interaction. To better characterize these processes, we investigate the present-day thermochemical structure (temperature and major-element composition) of the lithospheric and sub-lithospheric mantle. The thermal structure provides indirect information on variations in mantle viscosity, key parameter in glacial isostatic adjustment models (GIA). Recent geophysical studies in Antarctica show a relationship between mantle viscosity inferred from GIA and seismic velocity anomalies. Here we use a 3-D multi-observable probabilistic inversion method to retrieve estimates of the thermal and lithological structures (velocities and densities) beneath West Antarctica at a resolution of 1°x1°. The method is based on a probabilistic (Bayesian) formalism and jointly inverts Rayleigh wave dispersion data, bouguer gravity anomalies, satellite‐derived gravity gradients, geoid height, absolute elevation and surface heat flow. With the Markov chain Monte Carlo procedures applied here, we use highly optimized forward problem solvers to sample the parameter space and determine geological structure and feature with full characterization of their uncertainties. In this presentation, we will discuss the main results, interpretation in terms of mantle rheology, and its implication for GIA model in this region.
Sources of hazardous geoelectric fields in the United States during magnetic storms
Authors: Shi Xueling , Hartinger Michael , Baker Joseph , Bedrosian Paul , Murphy Benjamin , Kelbert Anna , Rigler Joshua , Ruohoniemi Michael
Published: March 2021

Geomagnetic perturbations related to various phenomena in the near-Earth space environment can induce electric fields within the electrically conducting Earth. The geoelectric field is an important link between magnetospheric/ionospheric phenomena and geomagnetically induced currents in grounded electricity transmission networks. In evaluations of contiguous United Sates hazards, most previous studies have been focused on either 1-minute resolution geoelectric field measurements or geoelectric field time series derived from convoluting 1-minute geomagnetic field data with surface impedance tensors. To investigate sources of hazardous geoelectric fields during magnetic storms, including geoelectric fields induced by ultra-low frequency (ULF: 1 mHz to 1 Hz) waves, we use directly measured 1-second geoelectric field data from magnetotelluric survey stations that are distributed across the contiguous United States. Temporally-localized perturbations in measured geoelectric fields with a prominence of at least 0.5 V/km are detected during magnetic storms with a Dst minimum of at least -100 nT from 2008 to 2019. Most of these perturbations cannot have been resolved with 1-minute data since they correspond to phenomena that vary on smaller timescales and higher frequencies. The sources of geomagnetic perturbations inducing these extreme geoelectric fields can be categorized as interplanetary shocks, substorms, and ULF waves. We compare the geoelectric fields associated with the three sources and characterize their features. Extreme geoelectric fields related to these sources can have amplitudes of 1-2 V/km, comparable to the thresholds commonly used to identify hazardous events.
On the stabilization of breather-type solutions of the  damped higher order nonlinear Schrödinger equation
Authors: Schober Constance
Published: March 2021

Spatially periodic breather solutions (SPBs) of the nonlinear Schrödinger  (NLS) equation are frequently used to model rogue waves and are typically unstable.  In this talk we examine the effects of dissipation and higher order nonlinearities on the stabilization of N-mode SPBs, 1 ≤ N ≤ 3, in the framework of a damped higher order NLS (HONLS) equation.  We observe the onset of  novel  instabilities  associated with the development of critical  states resulting from symmetry breaking  in the damped HONLS system. We develop a broadened Floquet characterization of  instabilities of solutions of  the NLS equation by showing that instabilities are  associated with degenerate complex elements of not only the discrete, but also the continuous Floquet spectrum. As a result, the Floquet criteria for the stabilization of a solution of the damped HONLS centers around the elimination of all complex degenerate elements of the spectrum. For  a given  initial N-mode SPB,  a short-time perturbation analysis shows that the  complex double points associated with resonant modes split under the damped HONLS while those associated with  nonresonant modes remain closed. The corresponding  damped HONLS numerical experiments corroborate that instabilities associated with  nonresonant modes persist  on a longer time scale than the instabilities associated with resonant modes.
  
Twin induced attenuation of seismic anisotropy in lawsonite blueschist
Authors: Choi Seungsoon , Fabbri Olivier , Topuz Gültekin , Okay Aral , Jung Haemyeong
Published: March 2021

Lawsonite is an important mineral to understand seismic anisotropy in subducting oceanic crust because of its large elastic anisotropy and prevalence in cold subduction zones. However, there is a lack of knowledge on how lawsonite twinning affects seismic anisotropy despite previous reports showing the existence of twins in lawsonite. We thus investigated the effect of twins in lawsonite on crystal preferred orientation (CPO), fabric strength, and seismic anisotropy of lawsonite using the lawsonite blueschists from Alpine Corsica (France) and Sivrihisar Massif (Turkey). CPOs of minerals were measured by using the electron backscattered diffraction (EBSD) facility attached to scanning electron microscope. The EBSD analyses of lawsonite revealed that {110} twin in lawsonite is developed and [001] axes are strongly aligned subnormal to the foliation and both [100] and [010] axes are aligned subparallel to the foliation. It is found that the existence of twins in lawsonite could induce a large attenuation of seismic anisotropy, especially for the maximum S-wave anisotropy up to 18.4 % in lawsonite and 24.3 % in the whole rocks. Therefore, lawsonite twinning needs to be considered in the interpretation of seismic anisotropy in the subducting oceanic crust in cold subduction zones.
Nature Based Solutions applied to road infrastructure in Nepal, a vehicle for development.
Authors: Vicarelli Marta , Sudmeier-Rieux Karen , Koirala Dhiroj , Devkota Sanjay
Published: March 2021

This article describes research undertaken in the Panchase Region of Western Nepal as part of the “Ecosystems Protecting Infrastructure and Communities” (EPIC) project 2012-2017, where three community-led bio-engineering demonstration sites were established along roadsides.  The topic of Nature Based Solutions (NBS) and Eco-DRR/CCA is explored adopting interdisciplinary research methods, spanning both social and physical sciences, and citizen science alongside state-of-the art high resolution erosion monitoring and remote sensing. We examine the nexus between infrastructure design (traditional roads vs green roads) and landslides. Investigations included a watershed study of land use changes over time and erosion rates associated with road construction in the Phewa Lake Watershed (Kaski district, Western Nepal), an analysis of the effectiveness of vegetation in reducing erosion rates using LIDAR and drone measurements, and a cost-benefit analysis of conventional “grey” versus bio-engineered roads, or “eco-safe roads”.

Results of the watershed study indicate a trend from erosion due to open grazing thirty years ago to increased erosion by new roads; Land IDAR measurements show that vegetation has been effective in reducing erosion rates. The cost benefit analysis (CBA) explores the net benefit of grey vs eco-safe roads using different time horizons and precipitation distributions associated to monsoonal activity and climate change trends. The CBA results demonstrate that initial costs in installing the bio-engineered eco-safe road are higher than for the “grey” road, however the bio-engineered road rapidly becomes more cost-effective, especially when factoring in avoided damages and multiple co-benefits to the population. Findings from this work have led to policy recommendations promoting and upscaling a more sustainable approach to bio-engineering for rural road construction in Nepal as well as methodological recommendations for replicating and up-scaling similar studies elsewhere.
High-pressure granulite facies metamorphism of Archean Bastar craton at the interface of Eastern Ghats Belt: Implications for cratonic subduction/underthrusting
Authors: Jayalekshmi Padmaja , Sarkar Tapabrato , Dasgupta Somnath , Bhutani Rajneesh
Published: March 2021

The Bastar Craton at the interface of Eastern Ghats Belt (EGB) contains a mélange of rocks from both the Archean cratonic domain and the adjacent Proterozoic mobile belt domain marking a broad shear zone, known as the Terrane Boundary Shear Zone (TBSZ). The TBSZ preserves a very rare occurrence of high-grade metamorphosed Archean cratonic rocks, whose ancestry has been constrained by Nd model ages. This study presents the petrological and geochemical characterization of mafic granulites and orthopyroxene bearing granitoids from the shear zone and its implications on the tectonic evolution of the craton – mobile belt boundary. Detailed petrographic, geothermobarometric and P-T pseudosection studies indicate that the Bastar cratonic rocks underwent high-pressure granulite facies metamorphism along a clockwise P-T path, reaching ~900°C and 9-10 kbar. The originally amphibolite facies rocks, metamorphosed through dehydration-melting of hornblende (mafic rocks) and biotite (felsic rocks), to attain the peak P-T conditions. We suggest that this high-grade metamorphism was due to the subduction/underthrusting of the Bastar Craton beneath the EGB, supported by the available seismic data, which resulted from far-field stress related to the Kuunga orogeny in an intraplate setting.
The standing biomass of saltmarshes as a key variable for estimating their wave energy damping capacity
Authors: Maza Maria , Lara Javier L. , Losada Iñigo J.
Published: March 2021

The estimation of wave energy dissipation produced by saltmarshes has traditionally been obtained in terms of a drag or friction force. The estimation of these forces is made taking into account the characteristics of the saltmarsh (i.e. biomechanical properties, morphology, density) and a hydrodynamic coefficient (i.e. the drag or friction coefficient). The characterization of a vegetated ecosystem by measuring leaf traits, the biomechanical properties of the plants and the number of individuals per unit area involves a lot of effort and is case-specific. In addition, hydrodynamic coefficients are selected on the basis of simplified geometry parameterizations or on calibrations performed in ad hoc studies and accurate estimates rely on their validation under real conditions.

Although for a very limited number of species, previous studies have shown that wave damping positively correlates with standing biomass. Therefore, standing biomass can be a unique variable that defines the wave energy attenuation capacity of the ecosystem. In addition, this variable has already been already characterized for many ecosystems by means of traditional plant harvesting or more recently using aerial images. Then, to further explore its relationship with the induced flow energy attenuation, a new set of experiments is proposed using real vegetation, with contrasting morphology and biomechanical properties, and subjected to different incident flow conditions. The experiments are carried out considering four species of vegetation, with contrasting biomechanical properties and morphology, and including two densities per species. Three water depths, wave heights from 0.08 to 0.18 m and wave periods from 1.5 to 4 s are tested. Capacitive free surface gauges and Acoustic Doppler Velocimeters (ADVs) are used to measure wave damping plant capacity along the meadow.

A direct relationship between the standing biomass of the meadow and plant induced wave attenuation is found for the eight vegetated conditions. In addition, a single relationship is obtained for the resultant wave damping and the eight standing biomass values. This relationship provides the basis for the use of standing biomass as a key parameter to estimate the coastal protection service provided by different saltmarsh species using a single variable that can be easily quantified from the field.
The effect of SARS-CoV-2 on atmospheric particulate matter (AOD) as observed by satellites
Authors: Margaritis Vasilis , Hatzianastassiou Nikolaos , Korras Carraca Marios Bruno , Gavrouzou Maria
Published: March 2021

After the outbreak of SARS-CoV-2 in December 2019 and its spread worldwide in the following months and seasons, the governments around the world were forced, one by one, to impose lockdown measures in their countries during the ‘Covid Year’ of 2020, trying to slowdown or even stop the spread of the virus. These nationwide lockdowns, included measures that led to the reduction of human movement, such as transportation, in urban areas, while they also diminished the industrial activity. Since transportation and industrial activity are among the major sources of emission of anthropogenic aerosols, it is possible that a change, namely a decrease, of the atmospheric aerosol loading is observed during the year 2020. 

In this study, we examine and quantify the possible effect of worldwide Covid19-related lockdowns on air quality, and more specifically on the aerosol optical depth, which is a good measure of aerosol loading. The analysis is done at global scale using Collection 6.1 Level-3 daily 1°x1° latitude-longitude gridded spectral Aerosol Optical Depth (AOD) data from Moderate Resolution Imaging Spectroradiometer (MODIS) on AQUA satellite during the period 2003-2020. We assess the possible anomaly in AOD values during 2020 by comparing their annual, seasonal and monthly mean values with the corresponding climatological ones for the period 2003-2019. A trend analysis is also performed using time series of deseasonalized AOD anomalies during the period 2003-2020. Special emphasis is given to specific great urban areas, as well as to areas where stricter measures were taken for limiting the virus’ spread. For these areas of interest, a further analysis using higher resolution (10km x 10km) MODIS Level-2  AOD data was made in order to capture local changes in AOD that could be hindered by the coarser resolution Level-3 data. Finally, for these regions, the AOD changes estimated using MODIS Level-2 data are intercompared with the corresponding ones using data from local AERONET (AErosol RObotic NETwork) stations. Preliminary results show a clear reduction in AOD values, mainly starting from April 2020 and becoming more clear in late spring and early summer (May and June) of 2020.
Value of multi-source dataset for hydrological catchment modeling 
Authors: Natel de Moura Carolina , Carvalho João Marcos , Seibert Jan
Published: March 2021

Global meteorological and hydrological datasets have become increasingly available in the past few decades, marked by an increase in the number of large datasets, often including hundreds of catchments. These data sets bring two main advantages: the ability to perform hydrological modeling over a large number of catchments located in different hydroclimate characteristics, - which leads us to more robust hypothesis testing, and the ability to address the uncertainties related to the hydrological model input data. However, the full added value to hydrological modeling is not yet fully understood. The main questions surrounding the use of multi-source and large-scale datasets are related to how much value these datasets add to the performance of hydrological models. How different are these datasets, how accurate are they, and whether their use results in similar or rather different hydrological simulations? Other questions are how can we better combine them for improved predictions, and what is the average uncertainty of the input datasets in hydrological modeling? We aimed here to investigate better those issues using Brazilian catchments as study cases. The Brazilian hydrometeorological network has several issues to overcome, such as an undistributed spatial network resulting in data-scarce areas, a large amount of missing data, and the lack of standardized and transparent quality analysis. In this study, we used a national hydrometeorological dataset (CAMELS-BR) along with other several global forecast and reanalysis meteorological datasets, such as the CFSv2 and ECMWF, for the streamflow prediction using the data-driven model Long-Short Term Memory (LSTM). Initial results indicate that calibrating a recurrent neural network is clearly depending on the data source. Moreover, the tested global meteorological products are found to be suitable for hydrological modeling. The combination of different data sources in the hydrological model seems to be beneficial, especially in those areas where ground-level gauge stations are scarce.
Fluid model of the plasma flow in the magnetic tail of a planet
Authors: Pantellini Filippo
Published: March 2021

All planets of the solar system with an active internal dynamo have a their magnetic dipole oriented perpendicularly or nearly perpendicularly to the solar wind during all or part of their orbit  around the Sun. If, in addition, the planetary rotation is slow, or if the angle between dipole and rotation axis is large, planetary field lines crossing the antisolar axis can become stretched to large distances downstream of the planet. Examples where this may occur are Mercury and Uranus at solstice time, respectively. 

Inspired by these examples, we present a tentative one-dimensional magnetohydrodynamic model of the plasma flowing along the antisolar direction. 

Assuming that the radius of curvature R(z) of the planetary field lines is defined locally as R=D/D', where D(z) is a characteristic  transverse scale of the magnetosphere at a distance z downstream of the planet,  we obtain that the plasma velocity u(z) obeys to a Hugoniot type equation  (M2-1) u'/u =  D'/D,  where M=u/vA is the Alfvén Mach number. 

The solution for a typical profile D(z) will be discussed. 
4 Ma-long uplift cycles of the southern Peru forearc since Late Miocene
Authors: Regard Vincent , Martinod Joseph , Saillard Marianne , Carretier Sébastien , Leanni Laetitia , Hérail Gérard , Audin Laurence , Pedoja Kevin
Published: March 2021

We explore the coastal morphology along an uplifting 500 km-long coastal segment of   the Central Andes, between the cities of Chala (Peru) and Arica (Chile). We use accurate DEM and field surveys to extract sequences of uplifted shorelines along the study area. In addition, we consider continental pediment surfaces that limit both the geographical and vertical extent of the marine landforms. We establish a chronology based on published dates for marine landforms and pediment surfaces. We expand this corpus with new 10Be data on uplifted shore platforms. The last 12 Ma are marked by three periods of coastal stability or subsidence dated ~12-11 Ma, ~8-7 Ma and ~5-2.5 Ma ago. The uplift that accumulated between these stability periods has been ~1000 m since 11 Ma; its rate can reach 0.25 mm/a (m/ka). For the last period of uplift only, during the last 800 ka, the forearc uplift has been accurately recorded by the carving of numerous coastal sequences. Within these sequences, we correlated the marine terraces with the sea level highstands (interglacial stages and sub-stages) up to MIS 19 (790 ka), i.e., with a resolution of ~100 ka. The uplift rate for this last period of uplift increases westward from 0.18 mm/a at the Peru-Chile border to ~0.25 mm/a in the center of the study area. It further increases northwestward, up to 0.45 mm/a, due to the influence of the Nazca Ridge. In this study, we document an unusual forearc cyclic uplift with ~4 Ma-long cycles. This periodicity corresponds to the predictions made by Menant et al. (2020) based on numerical models, and could be related to episodic tectonic underplating (subducting slab stripping) beneath the coastal forearc area.
The propagule method as a tool to study assemblage dynamics in benthic foraminifera: An example with pH variations
Authors: Weinmann Anna E. , Goldstein Susan T. , Triantaphyllou Maria V. , Langer Martin R.
Published: March 2021

Benthic foraminifera are important indicators for ecological studies. The assemblage composition of local communities can be used to analyze influences of environmental variables such as temperature, salinity, pH, and others. In recent years, the experimental propagule method has emerged as an effective tool to evaluate the influence of these variables on assemblage dynamics of benthic foraminifera. Propagules (tiny juveniles) of benthic foraminifera are widespread and can survive outside of a species’ natural distribution range. Their ability to become dormant and be re-activated once local conditions become suitable, is an important driver behind the capacity of foraminiferal assemblages to react quickly to environmental changes. In the laboratory, the propagules are first separated from the coarser fractions by sieving and then cultured under different conditions.

In the present study, we analyzed the effect of ocean pH on the composition of shallow-water assemblages from Corfu Island (Greece). Like other calcifying organisms, assemblages of foraminifera are susceptible to pH variations and have revealed compositional shifts along natural or experimental pH gradients. Our experimental set-up included four pH treatments between 6.5 and 8.5 at constant temperature and salinity (22°C and 38 ppt) for 5 weeks.

At the conclusion of the cultivation experiment, we found high numbers of grown specimens (825–1564 per replicate) and a high survivability rate throughout all treatments (78–87%). Higher pH (7.8 and 8.5) resulted in assemblages that were dominated by monothalamous and porcelaneous species, whereas lower pH (6.5 and 7.2) lead to a reduction in porcelaneous and an increase in agglutinated species. Several taxa showed significant positive or negative correlations with decreasing pH values.

Our results are congruent with previous findings that reported compositional shifts from calcareous to agglutinated taxa with decreasing pH (both from culture and field observations). Our study also indicates that the activation of propagules is an important mechanism behind assemblage dynamics in shallow-water foraminifera. As such, it offers an improved insight into potential resilience and recovery mechanisms of foraminiferal assemblages with regard to local or seasonal pH variations as well as ongoing ocean acidification.
Assembly patterns of the rhizosphere microbiome along the longitudinal root axis of maize (Zea mays L.)
Authors: Rüger Lioba , Kai Feng , Kenneth Dumack , Yan Chen , Ruibo Sun , Ye Deng , Frank Hochholdinger , Doris Vetterlein , Michael Bonkowski
Published: March 2021

This study was conducted within the framework of the DFG project SPP2089 “Rhizosphere Spatiotemporal Organization – a Key to Rhizosphere Functions”.

Different plant species select for individual subsets of bulk soil microbial communities within root systems. The fast variability of root environments implies that roots constitute highly dynamic habitats. Rapid root elongation, combined with widely varying quality and quantity of rhizodeposition between different root regions, lead to continuously changing conditions for colonizing microorganisms. As the microbiome concept implies a rather static outcome of the microbial assembly, it raises the question as to where and how the dynamic transition of a microbial bulk soil community into a plant species-specific rhizosphere microbiome is taking place.

To investigate the assembly of communities of prokaryotes and their microbial predators (Cercozoa, Rhizaria; protists) along the longitudinal root axis of maize (Zea mays L.), plants were grown in an agricultural loamy soil. Rhizosphere soil was sampled at distinct locations along roots. Diversity and co-occurrence of rhizosphere microbiota along the root axis were tracked by high-throughput sequencing, diversity measures and network analyses.

High variation in beta diversity at root tips and the root hair zone indicated substantial randomness of community assembly. Deterministic processes of community assembly were revealed by low variability of beta diversity, changes in network topology, and the appearance of regular phylogenetic co-occurrence patterns in bipartite networks between prokaryotes and their microbial predators. Deterministic processes were most robust in regions with fully developed lateral roots, suggesting that a consistent rhizosphere microbiome finally assembled. For the targeted improvement of microbiome function, such knowledge on the processes of microbiome assembly on roots and its temporal and spatial variability is of crucial importance.
Assessment of a newly developed short-term forecasting system (nextSENSE) of Downwelling Surface Solar Irradiance (DSSI) and validation with ground-based measurements
Authors: Papachristopoulou Kyriakoula , Fountoulakis Ilias , Kosmopoulos Panagiotis , Kouroutsidis Dimitris , Raptis Panagiotis I. , Kontoes Charalampos , Hatzaki Maria , Kazadzis Stelios
Published: March 2021

Monitoring and forecasting cloud coverage is crucial for nowcasting and forecasting of solar irradiance reaching the earth surface, and it’s a powerful tool for solar energy exploitation systems.

In this study, we focused on the assessment of a newly developed short-term (up to 3h) forecasting system of Downwelling Surface Solar Irradiation (DSSI) in a large spatial scale (Europe and North Africa). This system forecasts the future cloud position by calculating Cloud Motion Vectors (CMV) using Cloud Optical Thickness (COT) data derived from multispectral images from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the Meteosat Second Generation (MSG) satellite and an optical flow motion estimation technique from the computer vision community. Using as input consecutive COT images, CMVs are calculated and cloud propagation is performed by applying them to the latest COT image. Using the predicted COT images, forecasted DSSI is calculated using Fast Radiative Transfer Models (FRTM) in high spatial (5 km over nadir) and temporal resolution (15 min time intervals intervals).

A first evaluation of predicted COT has been conducted, by comparing the predicted cloud parameter of COT with real observed values derived by the MSG/SEVIRI. Here, the DSSI is validated against ground-based measurements from three Baseline Surface Radiation Network (BSRN) stations, for the year 2017. Also, a sensitivity analysis of the effect on DSSI for different cloud and aerosol conditions is performed, to ensure reliability under different sky and climatological conditions.

The DSSI short-term forecasting system proposed, complements the existing short-term forecasting techniques and it is suitable for operational deployment of solar energy related systems

Acknowledgements

This study was funded by the EuroGEO e-shape (grant agreement No 820852).
Developing a Sub-seasonal Forecasting System for Hydropower Reservoirs in Scotland 
Authors: Graham Robert M. , Browell Jethro , Bertram Douglas , White Christopher J.
Published: March 2021

Inflow forecasts play an essential role in the management of hydropower reservoirs. Forecasts help operators to mitigate flood risks, meet environmental requirements, and maximise the value of power generated. In Scotland, operational inflow forecasts for hydropower facilities are typically limited in range to 2 weeks ahead, which marks the predictability barrier of deterministic weather forecasts. Extending the horizon of these forecasts may allow operators to take more proactive responses to risks of adverse weather conditions, thereby improving water management and increasing profits.

This study outlines a method of producing skilful probabilistic inflow forecasts for hydropower reservoirs on sub-seasonal timescales (up to 6-weeks ahead), directly from Numerical Weather Prediction (NWP) model output. Using a case study site of a large hydropower reservoir in the Scottish Highlands, we use the European Centre for Medium-range Weather Forecasting (ECMWF) extended-range forecast to create probabilistic inflow forecasts for the reservoir. Inflow forecasts are derived by training a linear regression model for the observed inflow onto the NWP precipitation, and subsequently applying post-processing techniques from Ensemble Model Output Statistics.

We show that the inflow forecasts hold fair skill relative to climatology up to six weeks ahead. Average inflow forecasts for the period 1-35 days ahead hold good skill relative to climatology, and are comparably skilful to an average inflow forecast for the period 8-14 days ahead. Forecasts are more skilful in winter than summer, which is consistent with physical teleconnections from the tropics that operate on sub-seasonal timescales.

We further apply a stylised cost model that demonstrates the potential value of these forecasts through improved water management. The stylised cost model indicates that the sub-seasonal probabilistic inflow forecast are sufficiently reliable to improve decision making and deliver added value across all forecast horizons up to six weeks ahead, relative to climatological or deterministic forecasts.
Near-inertial internal waves in the Black Sea
Authors: Khimchenko Elizaveta , Ostrovskii Alexander , Klyuvitkin Alexey
Published: March 2021

The Black Sea is practically tideless basin where inertial variability dominates the energy spectra at the high-frequency band f > 1 day-1.  The near-inertial internal waves are easier to infer from the observational data in the absence of the tidal motions. Modern observing tools e.g., the temperature sensor strings, the ADCPs, and the profiler moorings allow for continuous measurements at fixed locations with high temporal resolution sufficient to resolve the inertial time scale.

Here we present an analysis of the time series of hydrophysical measurements both at the continental slope and in the deep central part of the Black Sea. The measurements over the continental slope were carried out using the Aqualog moored profiler with the CTD probe and acoustic Doppler current meter [1] in different seasons during 2015–2019. The time series of vertical profiles of temperature, salinity, density, dissolved oxygen, and current velocity were obtained for the water column from 20–30 m to 200–230 m depths. As for the deep basin measurements, these were done by using the moorings equipped with the temperature sensors and acoustic Doppler current meters at fixed depths of 100 m and 1700 m. The data included the year-long time series of temperature and current velocity from December 2016 to October 2017.

The vertical oscillations with a period close to the local inertial were clear cut in the multiparameter data vertical profiles in the main pycnocline at the continental slope. The examples of the near-inertial wave packs trapped in the pycnocline are shown. The maximum heights of the observed internal waves reached 30 m. During the passage of the near-inertial internal wave, the direction of the current changes to the opposite, which is typical for the first mode wave.

The seasonal variability of the near-inertial internal motions was studied by applying conventional statistical tools including spectral analysis to the mooring data in the Black Sea central part. It was found that intensification of inertial oscillations occurs from September to February. At the frequency close to the local inertial, the velocity rotation vector (hodograph) rotates clockwise, which is typical for inertial internal waves. The radius of the circle described by the vectors of the inertial currents varies within 0.5–1.5 km. The seasonal change of the cross-correlations between inertial motions in the upper and near-bottom layers was also revealed.

The research was conducted by the assignment of the Ministry of Science and Higher Education of Russian Federation No. 0149-2019-0011 and partly supported by RFBR grant No. 19-05-00459.      
Evaluation and analysis of riparian vegetation through satellite images
Authors: Alvarez Xana , Rivas Paula , Acña-Alonso Carolina , Valero Enrique
Published: March 2021

One of the main goals of the EU political agenda, supported by the green agenda, and one of the Sustainable Development Goals (SDGs) is the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services. Within these ecosystems is the riparian vegetation, an essential element in river ecosystems that influences the processes related to the surface and underground flow, modifying the temperature and humidity, it also functions as a filtering tool for the water. The riparian vegetation has been degraded as a cause of changes in land use, or the increase in population. In order to guarantee the biodiversity of ecosystems, as well as guarantee water security, it is necessary to explore environmental governance solutions. In this sense, new technologies can be useful tools that facilitate their characterization. For this reason, the feasibility of using satellite images has been evaluated to characterize the degradation of the riparian vegetation, facilitating decision-making by the administration. In this way, the improvement of riparian vegetation can be promoted, as a nature-based solution (NBs) with multiple environmental, social and economic benefits. Nowadays, there are multiples indices for determining the quality of riparian vegetation but all of them involve a high time, technical and economic effort. The implementation of solutions based on satellite images will improve and facilitate these actions. For this purpose, the images from the WorldView 2 satellite were analysed. The treating these images through geographic information systems, a scale is obtained that adapts to existing indices. With these new methods it would no longer be necessary to visit all the sample points, thus reducing the time to obtain results. The verification of the data obtained through the mapping of images (Riparian Strip Quality Index) was compared with data taken in the field (QBR index), obtaining a value of 92% of truthfulness, and a Kappa coefficient of 0.88 (very good). In other words, a methodology with high concordance with the data collected in situ was obtained. The application of this index through satellite images will facilitate the environmental governance of multiple ecosystems. Providing tools to implement best practices allowing an improvement of the NBs. In this way, biodiversity will be improved, and water quality will be improved, guaranteeing or improving water security, contributing to the achievement of the SDGs.
Public Outreach and Interactive Learning with En-ROADS Global Energy and Climate Simulator
Authors: Eker Sibel , Siegel Lori , Jones Charles , Sterman John , Kapmeier Florian , Fiddaman Tom , Homer Jack , Rooney-Varga Juliette , Franck Travis , Jones Andrew
Published: March 2021

Simple climate models enable not only rapid simulation of a large number of climate scenarios, especially in connection with the integrated assessment models of economy and environment, but also provide chances for outreach and education. En-ROADS, (Energy Rapid Overview and Decision Support)[1], is a publicly available, online policy simulation model designed to complement integrated assessment models for rapid simulation of climate solutions. En-ROADS is a globally aggregated energy-economy-climate model based on a simple climate model, and supports outreach and education about the causes and effects of climate change.  It has an intuitive user interface and runs essentially instantly on ordinary laptops and tablets, providing policymakers, other leaders, educators, and the public with the ability to learn for themselves about the likely consequences of energy and climate policies and uncertainties.

 

En-ROADS is a behavioral system dynamics model consisting of a system of nonlinear ordinary differential equations solved numerically from 1990-2100, with a time step of one-eighth year. En-ROADS extends the C-ROADS model, which has been used extensively by officials and policymakers around the world to inform positions of parties to the UNFCCC[2][3]. In En-ROADS’ climate module, the resulting emissions from the energy system, from forestry and land use, and carbon removal technologies, determine the atmospheric concentrations of each GHG, radiative forcing, and climate impacts including global surface temperature anomaly, heat and carbon transfer between the surface and deep ocean, sea level rise, and ocean acidification. It is calibrated to fit historical data of temperature change and carbon cycle elements, as well as the projections within the RCP-SSP framework. Both En-ROADS and C-ROADS are further developed to account for the details of the terrestrial carbon cycle.

 

 

 

 

[1] https://en-roads.climateinteractive.org/scenario.html.

[2] Sterman J, Fiddaman T, Franck TR, Jones A, McCauley S, Rice P, et al. Climate interactive: the C-ROADS climate policy model. System Dynamics Review 2013 28 (3): 295–305

[3] Sterman JD, Fiddaman T, Franck T, Jones A, McCauley S, Rice P, et al. Management flight simulators to support climate negotiations. Environmental Modelling & Software 2013, 44: 122-135.