bluuebunny/crossref_metadata_2025 huggingface dataset:
High-resolution ocean/sea ice/ice shelf simulation of the 79° North Glacier and Zachariae Isstrøm
Authors: Wekerle Claudia , Timmermann Ralph , Wang Qiang , McPherson Rebecca
Published: March 2021

The 79° North Glacier (79NG) is the largest of the marine terminating glaciers fed by the  Northeast Greenland Ice Stream (NEGIS), which drains around 15% of the Greenland ice sheet. The 79NG is one of the few Greenland glaciers with a floating ice tongue, and is strongly influenced by warm Atlantic Water originating from Fram Strait and carried towards it through a trough system on the Northeast Greenland continental shelf.

Considering the decrease in thickness of the 79NG and also of the neighboring Zachariae Isstrøm (ZI), we aim to understand the processes that potentially lead to the decay of these glaciers. As a first step we present here an ocean-sea ice simulation which explicitly resolves the cavities of the 79NG and ZI glaciers, applying the Finite-Element Sea ice-Ocean Model (FESOM). We take advantage of the multi-resolution capability of FESOM and locally increase mesh resolution in the vicinity of the 79NG to 700 m. The Northeast Greenland continental shelf is resolved with 3 km, and the Arctic Ocean and Nordic Seas with 4.5 km. The simulation is conducted for the time period 1980 to 2018, using JRA-55 atmospheric reanalysis. Solid and liquid runoff from Greenland is taken from the Bamber et al. 2018 dataset. The flow of warm Atlantic water into the glacier and outflow of meltwater is compared to observational data from measurement campaigns. We further use current and hydrographic data from moorings deployed in Norske Trough to assess the model performance in carrying warm water towards the glacier. This simulation spanning several decades allows us to investigate recent changes in basal melt rates induced by oceanic processes, in particular warm Atlantic Water transport towards the glacier.
Spatio-temporal variability of global crop water requirement, during 1950-2020
Authors: Rolle Matteo , Tamea Stefania , Claps Pierluigi
Published: March 2021

Intensification of studies of the agricultural water requirement is a main challenge in a globalized world, where food production is pushed to meet the needs of a growing population and the international trade network requires large-scale planning policies. Agriculture is the human activity that consumes most of the withdrawn freshwater and climate change can greatly influence the amount of irrigation required by crops. In recent years, the widespread availability of satellite images is providing an important contribution to water resources management, offering data at high spatio-temporal resolution over an interestingly long period of time.

This study deals with the temporal variability of global water requirement of the main crops, which is assessed through a comprehensive model, driven by climate forcings, that estimates the daily crop water requirement on a spatial resolution of 5 arc-min (or 0.0833°) from 1950 to 2020. The model computes a soil water balance using daily input data of precipitation and evapotranspiration, based on the high-resolution ERA5 reanalysis dataset from the Climate Change Service of the Copernicus Program, which combines satellite information and ground measurements. The distribution of harvested areas and the length of crop development phases are kept constant, to analyze the variability of crop water requirement strictly related to climate forcings, both in terms of precipitation (green water) and irrigation (blue water). The model considers the separation between irrigated and rainfed areas, in order to provide a consistent spatial distribution of irrigation requirements. Examining the spatio-temporal variability of the crop water requirement can support considerations on the effects of global warming in different areas in the world.
Monitoring of long-range transported smoke in polar regions with remote sensing instruments
Authors: González Catón Ramiro , Toledano Carlos , Román Diez Roberto , Mateos David , Asmi Eija , Rodriguez Edith , Antuña-Sánchez Juan Carlos , Herrero Sara , Cachorro Victoria E. , Calle Abel , de Frutos Ángel M.
Published: March 2021

Long range transported aerosol from biomass burning affects polar regions, especially the Arctic. The frequency and intensity of bushfires in the context of a warming climate has been pointed out in the last report of the Intergovernmental Panel on Climate Change. In high latitudes, these events impact large areas through long-range transport of the smoke particles in the troposphere or even the stratosphere. The lifetime and radiative impact are related with the height of the plumes and the processes that modify particle size and absorptive properties during the transport. Several recent publications have shown the impact of the Australian smoke in the southern hemisphere, including Antarctica, in January-March 2020. The tools that were used to monitor that extraordinary event can be used in the Arctic to investigate similar effects in the frequent biomass burning events that generate smoke plumes in boreal regions. In this work, we present the results derived from ground-based instrumentation as well as satellite and model data. The change of the smoke properties after several days of transport is also provided, namely an increase in the fine mode particle size and the single scattering albedo, as well as a decrease in the coarse mode particle concentration. These features are relevant for radiative forcing calculations and therefore the impact of long range transported smoke in the radiative balance over polar regions.
Periodic alterations of the hydrological exchange in hyporheic sediments: colmation, hyporheic fauna and abiotic parameters in a second order stream during one year 
Authors: Stein Heide , Hahn Hans Jürgen
Published: March 2021

In this study, the temporal variability of the hydrological exchange between stream water (SW) and groundwater (GW), colmation, hyporheic invertebrate fauna, organic matter (OM) and physicochemical parameters were examined for the period of one year. Sampling and measuring were conducted monthly from May 2019 to April 2020 at the Guldenbach river, a second order stream in Rhineland-Palatinate, Germany. All hyporheic samples were extracted from a depth of 15 cm below stream bottom. Colmation was measured quantitatively in the same depth.

Following the biotic and abiotic patterns found, three temporal stages of different hydrological conditions can be described:

1) Strong floods, in February and March 2020 caused hydromorphological alterations of the river bed, leading to a decolmation of the hyporheic zone, a wash out of OM and hyporheic fauna. Due to high GW tables the vertical hydrological gradient (VHG) was positive indicating upwelling GW.

2) In the months of Mai to August 2019 and April 2020, precipitation and stream discharge were lowest. Predominantly exfiltrating conditions were observed, while the amount of fine sediments (clay and silt) increased as well as colmation. High densities of hyporheic fauna, dominated by fine sediment dwelling taxa, were assessed.

3) From September 2019 to January 2020 stream discharge was low. The VHG became increasingly negative, indicating downwelling SW. In accordance, colmation increased continuously, while densities of hyporheic invertebrates decreased and sediment dwellers became more dominant.

Precipitation, discharge events and GW table were found to be the driving factors for the annual dynamics of the hydrological exchange as well as for colmation, fauna and hydrochemistry. Electric conductivity seems a suitable indicator for the origin of water with high values in months of low precipitation and lower values after extensive precipitation events, respectively. Hyporheic fauna displayed a significant seasonality and the community structure was correlated with colmation and changes in the VHG.

This pronounced seasonality seems to be typical of many streams and should be considered for the monitoring of sediments and hyporheic habitats: Seasons with lower stream discharge are probably the most critical periods for sediment conditions.

We assume that the basic patterns of the dynamics observed basically reflect the natural situation in the catchment. However, the strength of surface run-off and the amount of fine sediments are mainly the result of anthropogenic activities and land use in the catchment.

These findings underline the significance of dynamical processes for the assessment and implementation of the Water Framework Directive.
The relation between the zonal jets and ammonia anomalies in Jupiter
Authors: Gavriel Nimrod , Duer Keren , Galanti Eli , Kaspi Yohai ,   Juno MWR team
Published: March 2021

Juno's six‐channel MWR measurements might reveal information about the structure of the wind profile below the cloud level. These measurements are used to calculate the nadir brightness temperature (Tb), a profile determined by temperature and by the opacity of the atmosphere. This opacity for the relevant frequencies of the MWR is determined mostly by ammonia abundance. The Tb vary considerably between the different channels (indicating on different depths) and between latitudes. Here, we take the  Tb as an indicator for ammonia concentration and examine the relation to the zonal jets. We find that different theoretical mechanisms can explain this relation at different latitudes. At the equatorial region, the superrotation is accompanied by vertical upwelling. This vertical advection, driven by a convergence of eddy fluxes directed perpendicular to the axis of rotation, is shown to explain the equatorial ammonia enrichment. At the mid-latitudes, assuming that the ammonia is enriched with depth, alternating Ferrel-like cells framed by opposite vertical velocities redistributes the ammonia, maximizing its meridional gradient where the jet peaks. This hypothesis is well apparent in the data, using both correlation analysis and theoretical arguments. We find that dynamical reasoning, suggesting on vertical velocities through the cloud-level zonal jets, can explain the latitudinal variations in  Tb, under the assumption that they are caused by ammonia abundance anomalies.
Natural gas shortages during the “coal-to-gas” transition in China have caused a large redistribution of air pollution in winter 2017
Authors: Wang Siwen , Su Hang , Chen Chuchu , Tao Wei , Streets David , Lu Zifeng , Zheng Bo , Carmichael Gregory , Lelieveld Jos , Pöschl Ulrich , Cheng Yafang
Published: March 2021

Improving air quality is an important driving force for China’s move toward clean energy. Since 2017, the “coal-to-gas” and “coal-to-electricity” strategies have been extensively implemented in northern China, aiming at reducing dispersed coal consumption and related air pollution by promoting the use of clean and low-carbon fuels. Our analyses show that on top of meteorological influences, the effective emission mitigation measures achieved an average decrease of fine particulate matter (PM2.5) concentrations of ∼14% in Beijing and surrounding areas (the “2+26” pilot cities) in winter 2017 compared to the same period of 2016, where the dispersed coal control measures contributed ∼60% of the total PM2.5 reductions. However, the localized air quality improvement was accompanied by a contemporaneous ∼15% upsurge of PM2.5 concentrations over large areas in southern China. We find that the pollution transfer that resulted from a shift in emissions was of a high likelihood caused by a natural gas shortage in the south due to the coal-to-gas transition in the north. The overall shortage of natural gas greatly jeopardized the air quality benefits of the coal-to-gas strategy in winter 2017 and reflects structural challenges and potential threats in China’s clean-energy transition. Our finding highlights the importance and necessity of synergy between environmental and energy policymaking to address the grand challenge of an actionable future to achieve the cobenefits of air quality, human health, and climate.
Prediction of above ground biomass and C-stocks based on UAV-LiDAR,multispectral imagery and machine learning methods.
Authors: Caballer Revenga Jaime , Trepekli Katerina , Oehmcke Stefan , Gieseke Fabian , Jensen Rasmus , Friborg Thomas
Published: March 2021

Current efforts to enhance the understanding of global carbon (C) cycle rely on novel monitoring campaigns of C sequestration in terrestrial ecosystems.The successful outcome of such efforts will be relevant to sectors ranging from climate change and land use studies (global scale) to precision agriculture and land management consultancy (local scale).To that end, current investigations apply recently developed scientific instrumentation - e.g.  Light detection and Ranging (LiDAR) -  and computational methods - e.g. Machine Learning (ML). Near-field remote sensing - i.e.  Unmanned Aerial Vehicle (UAV)-LiDAR -, can provide high resolution LiDAR data, increasing the monitoring accuracy of C stocks estimates and biophysical variables at the ecosystem scale. In contrast to previous approaches (e.g. image-derived vegetation indices), UAV-LiDAR provides a true 3D description of the canopy vertical structure. In order to evaluate the potential of new approaches towards precise C stock quantification in an agricultural field of Denmark (13 ha.), using near-field remote sensed data, we compare the results based on using 3D canopy metrics - derived from UAV-LiDAR - against the well-established multispectral image based metrics. Then, the performance of six different machine learning (ML) models  - two Random Forest variations, KNN, AdaBoost, ElasticNet, Support Vector, and Linear regression - designed to predict above ground biomass (AGB) based on a set of features derived from (i) UAV-LiDAR point cloud data (PCD), and (ii) multispectral imagery is evaluated. Their prediction quality are tested against unseen data from the same species, and sampling campaigns. Also, the sources of uncertainty are assessed as well as the importance of each predicting feature. The field work was conducted within the footprint of an Integrated Carbon Observation System (ICOS) class 1 station site, facilitating ecosystem traits monitoring in real time. The aerial and biomass sampling campaigns have been operated at 15-days frequency during the crops' growing period, in which, simultaneously, UAV-LiDAR and multispectral image data as well as ground truth biomass data were collected. By means of laboratory analysis, C and nutrient content in the crops' biomass was also determined. Based on arithmetic and morphological methods, the PCD were pre-processed to remove noise and classify them to ground and vegetation points. By means of the methods described, we demonstrate that UAV-LiDAR combined with multispectral data and ML methods can be used to accurately estimate AGB, 3D ecosystem structure as well as C-stocks in agricultural ecosystems. 
Eddy covariance flux measurements of momentum, heat and carbon dioxide in Hudson Bay at the onset of sea ice melt 
Authors: Sims Richard , Butterworth Brian , Papakyriakou Tim , Ahmed Mohamed , Else Brent
Published: March 2021

Remoteness and tough conditions have made the Arctic Ocean historically difficult to access; until recently this has resulted in an undersampling of trace gas and gas exchange measurements. The seasonal cycle of sea ice completely transforms the air sea interface and the dynamics of gas exchange. To make estimates of gas exchange in the presence of sea ice, sea ice fraction is frequently used to scale open water gas transfer parametrisations. It remains unclear whether this scaling is appropriate for all sea ice regions. Ship based eddy covariance measurements were made in Hudson Bay during the summer of 2018 from the icebreaker CCGS Amundsen. We will present fluxes of carbon dioxide (CO2), heat and momentum and will show how they change around the Hudson Bay polynya under varying sea ice conditions. We will explore how these fluxes change with wind speed and sea ice fraction. As freshwater stratification was encountered during the cruise, we will compare our measurements with other recent eddy covariance flux measurements made from icebreakers and also will compare our turbulent CO2 fluxes with bulk fluxes calculated using underway and surface bottle pCO2 data. 

 
Computing a Groundwater Sustainability Index for coastal aquifers in Portugal and California to foster sustainable groundwater management
Authors: Malmgren Katherine , Neves Maria da Conceição
Published: March 2021

Sustainability Indices can be useful to quantify objective groundwater management strategy outcomes, particularly across regional scales and when local groundwater budget data is not readily available. Previous studies have used performance indicators to evaluate surface water systems, and their application to groundwater is expanding to address water availability concerns. Here, a groundwater sustainability index (GSI) is computed across coastal aquifer systems in Portugal and California using reliability (REL), resilience (RES), and vulnerability (VUL) performance indicators. Aquifers in these Mediterranean climate zones are susceptible to inter-annual and seasonal water storage fluctuations linked to climate forcings and drought. Piezometric levels in the selected aquifers in Portugal (Leirosa-Monte Real and Campina de Faro) and California (Napa and Santa Barbara), spanning a period from 1989 to 2019, are analyzed using a point-wise approach to provide an index-per-piezometer. The computation exposes that the resilience indicator is heavily influential in setting an aquifer system's overall sustainability classification. However, the most significant output from the GSI is a clear indication of how well (or poor) a specific aquifer can withstand drought conditions that occur in both California and Portugal throughout the 30-year span of this study. Lastly, comparing indices with different priorities (performance indicators), such as sustainability and exploitive use (including the Water Framework Directive’s River Basin Management Plan’s Water Exploitation Index (WEI+)) can help identify aquifer systems that may need an immediate policy, conservation, or mitigation interventions, and others that may be self-sustaining for a longer period of time. The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL.
Soil respiration under different agricultural land use types in Croatia
Authors: Bilandžija Darija , Galić Marija , Zgorelec Željka
Published: March 2021

In order to mitigate climate change and reduce the anthropogenic greenhouse gas (GHG) emissions, the Kyoto protocol has been adopted in 1997 and the Paris Agreement entered into force in 2016. The Paris Agreement have ratified 190 out of 197 Parties of the United Nations Framework Convention on Climate Change (UNFCCC) and Croatia is one of them as well. Each Party has obliged regularly to submit the national inventory report (NIR) providing the information on the national anthropogenic GHG emissions by sources and removals by sinks to the UNFCCC. Reporting under the NIR is divided into six categories / sectors, and one of them is land use, land use change and forestry (LULUCF) sector, where an issue of uncertainty estimates on carbon emissions and removals occurs. As soil respiration represents the second-largest terrestrial carbon flux, the national studies on soil respiration can reduce the uncertainty and improve the estimation of country-level carbon fluxes. Due to the omission of national data, the members of the University of Zagreb Faculty of Agriculture, Department of General Agronomy have started to study soil respiration rates in 2012, and since then many different studies on soil respiration under different agricultural land uses (i.e. annual crops, energy crop and vineyard), management practices (i.e. tillage and fertilization) and climate conditions (i.e. continental and mediterranean) in Croatia have been conducted. The obtained site specific results on field measurements of soil carbon dioxide concentrations by in situ closed static chamber method will be presented in this paper.
A comparison of the microphysics dependency on the reproducibility of the MJO under different resolutions using NICAM
Authors: Suematsu Tamaki , Yamada Yohei , Kodama Chihiro , Miyakawa Tomoki
Published: March 2021

Simulation of the Madden-Julian Oscillation (MJO) has been notoriously difficult in atmospheric models. This is partly due to the fact that the reproducibility of the MJO is highly sensitive to parameters that are difficult to fix from observation or theory, and require empirical tuning based on model behaviors. Parameters regards to the cloud-microphysics are some of such parameters that simulations of the MJO are especially sensitive to.

To address this problem, we conducted a set of cloud-microphysics parameter-sweep experiments on a convection-permitting model, NICAM (Nonhydrostatic ICosahedral Atmospheric Model) at 14 km horizontal resolution to seek for a setting which best represents the MJO (MJO-tuned). We then compared the performance of the NICAM in reproducing the MJO using MJO-tuned setting with the standard NICAM setting employed for high resolution model intercomparison project (High Res MIP)-type experiments. The comparison was conducted for 14 km resolution, and for 3.5 km resolution experiments using DYAMOND (DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains) data, which is based on the MJO-tuned setting.

The comparison indicated that in the 14 km resolutions, the MJO-tuned setting reduces the excessive development of convection over the Maritime Continents which was apparent in the High Res MIP-setting. However, for the 3.5 km experiments convective activities of the MJO appeared to successfully reach the dateline for both the MJO-tuned setting and the High Res MIP-setting. The results of this study implies that a sufficient increase in the horizontal resolution has the potential to reduce the dependency of the microphysics setting on the reproducibility of the MJO, at least in the first few weeks of the simulations on NICAM.
Flood forecasting system for Brahmaputra river basin 
Authors: Kale Akash , Mishra Vimal
Published: March 2021

Assam has always been India’s most flood prone state due to the presence of Brahmaputra river, which is very unstable in terms of its flow direction witnessing 12 major floods from 1950 to 2012. Flooding in the basin has affected around 2.75 million of people and 0.27 million hectares of agricultural land on an average causing catastrophic damage to human life and infrastructure. In this study, we analysed all the major floods across the Brahmaputra river in the past 70 years and established the dependency within discharge and atmospheric parameters. Variable Infiltration Capacity (VIC) model was set up to simulate the flow at two stations namely Yangcun, China and Bahadurabad, Bangladesh. We  used near surface meteorological data for driving land surface modelling systems from 1901 to 2016 as input parameters to the VIC model. To avoid the discontinuity of data after 2016, we used ECMWF reanalysis (ERA5) data for the period of 2016 to 2020. After obtaining the continuous simulated discharge for 120 years, we established the relationship between the observed and simulated discharge data for which the R-squared and Nash Sutcliffe coefficient values were 0.83 and 0.78 respectively. Comparing the simulated discharge with the observed extreme discharge at various locations on the river, we apply the model to address future flood situations.
The effect of the GIA feedback loop on the evolution of the Antarctic Ice sheet over the last glacial cycle using a coupled 3D GIA – Ice Dynamic model
Authors: van Calcar Caroline , de Boer Bas , Blank Bas , van de Wal Roderik , van der Wal Wouter
Published: March 2021

The Earth’s surface and interior deform due to a changing load of the Antarctic Ice Sheet (AIS) during the last glacial cycle, called Glacial Isostatic Adjustment (GIA). This deformation changes the surface height of the ice sheet and indirectly the groundling line position. These changes in surface height and grounding line position influence the evolution of the AIS and consequently, again the load on the Earth’s surface. As a result, GIA operates as a negative feedback loop and could stabilize the evolution of the AIS. This feedback maybe particularly relevant for relatively low viscosities of the mantle in West Antarctica which lead to a relatively fast response time of the bedrock due to changes in the West Antarctic Ice Sheet loading. Most studies capture this process by ignoring lateral variations in the viscosity of the mantle and the stabilizing GIA feedback loop. Here we present a new method to couple an ice sheet model to a GIA model at a variable timestep in the order of a thousand years. Several experiments have been done using different radial and lateral varying rheologies for simulations of the last glacial cycle. It is shown that the effect of including lateral variations and accounting for the stabilizing GIA feedback is up to 80 kilometers for the grounding line position and 400 meters for the ice thickness. The largest differences are observed close to the grounding line of the Ronne ice shelf and at several locations in East Antarctica. The total ice volume of the AIS increases by 0.5 percent over 5000 years when including the 3D GIA feedback loops in the coupled model. These results quantify the local importance of including GIA feedback effects in ice dynamic models when simulating the Antarctic Ice Sheet evolution over the full glacial cycle.  
In-situ observations of aerosol-cloud interactions in Ny-Ålesund, Svalbard, during fall 2019 and spring 2020
Authors: Motos Ghislain , Georgakaki Paraskevi , Zieger Paul , Wieder Jörg , Lohmann Ulrike , Nenes Athanasios
Published: March 2021

The Arctic region suffers an extreme vulnerability to climate change, with an increase in surface air temperatures that have reached twice the global rate during several decades (McBean et al., 2005). The role of clouds, and in particular low-levels clouds and fog, in this arctic amplification by regulating the energy transport from and to space has recently gained interest among the scientific community. The NASCENT 2019-2020 campaign (Ny-Ålesund AeroSol Cloud ExperimeNT) based in Ny-Ålesund, Svalbard (79º North) aimed at studying the microphysical and chemical properties of low-level clouds using measurements both at the sea level and at the Zeppelin station (475 m a.s.l.). Specifically, the susceptibility of droplet formation, which has recently been shown to be highly dependent on aerosol levels in European alpine valleys (Georgakaki et al., under review), could strongly vary between the fall to winter months, with pristine-like conditions, and the higher particle concentrations generally found in spring, known as the arctic haze. First results using a scanning mobility particle sizer (SMPS) and a cloud condensation nuclei counter (CCNC) confirmed that aerosol concentrations in the range 10 < Dpart [nm] < 500 were approximatively 4-5 times higher during the months of spring 2021 compared to those of fall 2020. In addition, we found relatively low values of the aerosol hygroscopic parameter κ, generally below 0.3, consistently with previous studies in the arctic region (Moore et al., 2011).

 

Georgakaki, P., Bougiatioti, A., Wieder, J., Mignani, C., Kanji, Z. A., Henneberger, J., Hervo, M., Berne, A. and Nenes, A.: On the drivers of droplet variability in Alpine mixed-phase clouds, , 34, under review.

McBean, G., Alekseev, G., Chen, D., Førland, E., Fyfe, Groisman, J., P. Y., King, R., Melling, H., Voseand, R., Whitfield, P. H.: Arctic climate: past and present. Arctic Climate Impacts Assessment (ACIA), C. Symon, L. Arris and B. Heal, Eds., Cambridge University Press, Cambridge, 21-60, 2005.

Moore, R. H., Bahreini, R., Brock, C. A., Froyd, K. D., Cozic, J., Holloway, J. S., Middlebrook, A. M., Murphy, D. M. and Nenes, A.: Hygroscopicity and composition of Alaskan Arctic CCN during April 2008, Atmospheric Chemistry and Physics, 11(22), 11807–11825, https://doi.org/10.5194/acp-11-11807-2011, 2011.
A Preliminary Assessment of Low-Cost Bridge Scour Monitoring Methods and Tools
Authors: Koursari Eftychia , Wallace Stuart , Michalis Panagiotis , Valyrakis Manousos , Paton Scott
Published: March 2021

Scour is a major cause of bridge collapse worldwide.

Climate change has resulted in flood events increasing both in frequency and in magnitude. Climate change, together with the current uncertainty about maximum scour depth around structures, make scour and other hydraulic actions some of the most important challenges for engineering going forward.

This study offers a preliminary assessment of bridge scour monitoring methods considering scour as a dynamical earth surface shaping process, and discusses how these methods can be used to improve predictive models for bridge scour depth.

Current methods used to monitor scour are mostly reactive. A vast amount of research has been carried out, aiming towards the implementation of various approaches to assist in the monitoring of scour; however, most methods used are either still reactive, or extremely costly and therefore not practical to be used for small to medium scale structures. This study aims in addressing major challenges faced by establishing a new, innovative framework for the monitoring of scour, while considering relevant approaches in literature. It discusses the development of an innovative, sustainable and low-cost framework, that can be used for small to medium scale structures. This will ensure a proactive response in the event of catastrophic scour occurring, safeguarding infrastructure and the travelling public.
Validation of tropospheric ties at the test setup GNSS co-location site in Potsdam
Authors: Kitpracha Chaiyaporn , Heinkelmann Robert , Ramatschi Markus , Balidakis Kyriakos , Männel Benjamin , Schuh Harald
Published: March 2021

Atmospheric ties are induced by differences between the set-up of observing geodetic systems at co-location sites, are mainly attributed to frequency and position, and are usually quantified by zenith delay and gradient component offsets derived by weather models or in situ instuments.. Similar to local ties, they could be applied to combine datasets from several space geodetic techniques, thus contributing to the improvement of the realization of terrestrial reference frames (TRF). Theoretically, atmospheric ties are affected only by the height differences between antennas at the same site and meteorological conditions. Therefore, atmospheric ties could be determined analytically based on meteorological information from in situ measurements or weather models. However, there is often a discrepancy between the expected zenith delay differences and those estimated from geodetic analysis, potentially degrading a combined atmospheric ties solution should tight constraints be used. In this study, we set up a GNSS experiment campaign on the rooftop of a building in Telegrafernberg that offers unobscured data coverage for one month. We compared the estimated zenith delay and gradients from GNSS stations in this experiment, applying atmospheric ties from (1) meteorological data from the Global Pressure and Temperature model 3 (GPT3), (2) ERA5 reanalysis, and (3) in-situ measurements, as well as corrections derived from ray tracing (Potsdam Mapping Functions, PMF). The results show that atmospheric ties employing GPT3, ERA5, in-situ measurements, and ray tracing has an excellent and comparable performance in term of bias mitigation, but not in term of standard deviation, for zenith delay. Moreover, the unexpected bias in zenith delay was identified in the antenna with radome installation. A significantly large bias was identified in estimated gradients; the source of this discrepancy has been traced back to unmitigated multipath effects in this experiment.
A new database for Intense Mediterranean Cyclones 
Authors: Alvarez-Castro M. Carmen , Gallego David , Ribera Pedro , Peña-Ortiz Cristina , Faranda Davide
Published: March 2021

To better assess the future risks associated with Intense Mediterranean Cyclones (IMC) a better understanding of their features, variability, frequency and intensity is required, including a robust detection method. The application of different detection algorithms provides results that are remarkably similar in some aspects but may be very different in others even using the same data. Thus, the selection of a particular method can significantly affect the results. For these reasons it is necessary to use different approaches and datasets to study the sensitivity and robustness of the detection approach. Those approaches often use minima in sea-level pressure (SLP) or extrema in relative vorticity or both to first identify the eye of the cyclone. SLP reflects the atmospheric mass distribution, and is representative of synoptic-scale atmospheric processes. On the other hand, the relative vorticity displays higher variability and is representative of the atmospheric circulation, being able to detect several local extrema (more than one centre), it can reduce uncertainties in the cyclone detection and tracking.

Therefore, within the framework of the EFIMERA project and to detect and track IMC we use a combination of different methods based on previous studies found in the literature. This new list of detected IMC events, together with the observed and well documented ones, are used here to create a new IMC database to be used for the study of their impacts and risk associated.
Sizes of solar radio sources observed by LOFAR
Authors: Gordovskyy Mykola , Kontar Eduard , Clarkson Daniel , Browning Philippa
Published: March 2021

Decametric radio emission provides a unique insight into the physics of solar and heliospheric plasmas. Along with dynamic spectra, the spatial characteristics of the emission sources observed in solar radio bursts yield important information about the behaviour of high-energy non-thermal electrons, and the state of thermal plasma in the upper solar corona. Recently, it has been shown that sizes and locations of radio sources in the 10-100 MHz range can be used as a diagnostic tool for plasma turbulence in the upper corona and inner heliosphere. However, observations in this spectral range can be strongly affected by limited spatial resolution of the instrument, as well as by the effect of the Earth's ionosphere on radio wave propagation.

We describe a new method for correcting radio intensity maps for instrumental and ionospheric effects using observations of a known radio source at an arbitrary location in the sky. Based on this method, we derive sizes and areas of the emission sources in the solar radio bursts observed by the Low-Frequency Array (LOFAR) in 30-45 MHz range. It is shown that the sizes of sources are of the order of ten arcminutes and decrease with increasing frequency. Overall, we find that the sizes and their variation, as well as the shapes of the sources in the considered events are consistent with the theoretical models of turbulent radio-wave scattering in the solar corona  developed by Kontar et al. 2019 (Astrophys.J., 884, 122).
Infrasound station IS25 of the International Monitoring System of the Comprehensive Test Ban Treaty : from design to certification
Authors: philippe thomas , carre sylvain
Published: March 2021

CEA is operating the French segment of the International Monitoring System of the Comprehensive Test Ban Treaty (CTBT). Construction of IMS stations was started on the late 90’ and one last station was pending before completing commitment of France.

Taking into account experience learned over the years, design was thought to combine enhanced detection capability and robustness. It gives also the opportunity to improve out monitoring tools and technics.

Station run 9 sensors spread out on a deep forest in Guadeloupe; power is distributed with buried cable while data are received with optical fibre to a central facility from which frames are sent to the International Data Center to the CTBTO. Constructiion was carried out in 2019.

IS25 was certified by the PTS of the CTBTO in November 2020
Confronting shell morphodynamics and sclerochronology: leaving behind phenomenology to move toward integrative laws of growth
Authors: Guarini Jennifer , Guarini Jean-Marc
Published: March 2021

Sclerochronological methods are described as a means to reconstruct, from increments recorded on a shell transect (i.e. "sclerochonological growth"), the fluctuations in past environments. This was proposed by an erroneous analogy with tree-ring dendrochronology. However, shells do not grow like trees. Almost all molluscan shells grow by adding increments at the shell edge, while preserving their shape. This is called "terminal growth". The advantage of this property is that there is a generic mathematical model that can quantify the shell expansion (morphological growth). 

Nonetheless, this generic model is not compatible with observed shell incrementation and accretion processes. This is because increment widths should increase geometrically in the mathematical model along a transect. We remarked that despite studying the same object, morphodynamics and sclerochronology have followed divergent paths in past decades, without incorporating advances of the other speciality. 

We have now addressed this problem head-on by developing a new mathematical framework to combine incremental shell growth within shell morphodynamics. This model is designed to be able to confront a theoretical prediction of shell incrementation with a measured one. The method combines morphodynamic modelled shapes with 3D shell scans and increments measured from shell transects. 

Our work in this area highlights several heretofore unrecognized fundamental problems in morphodynamics and sclerochronology which concern the way individual variability is accounted for in both areas. Regarding the reconstruction of environmental trends, we find that the arbitrary choice of one particular "best" shell transect and averaging over groups of individuals can be a source of significant bias. It is time to revise shell science methods to consider the entire incremental geometry (or growth 'ring') so that unbiased estimates of environmental changes can be provided using sclerochonological data. 
PICASSO: The Golden CubeSat
Authors: Baker Noel , Anciaux Michel , Demoulin Philippe , Fussen Didier , Pieroux Didier , Ranvier Sylvain
Published: March 2021

Led by the Belgian Institute for Space Aeronomy, the ESA-backed mission PICASSO (PICo-Satellite for Atmospheric and Space Science Observations) successfully launched its gold-plated satellite on an Arianespace Vega rocket in September 2020. PICASSO is a 3U CubeSat mission in collaboration with VTT Technical Research Center of Finland Ltd, AAC Clyde Space Ltd. (UK), and the CSL (Centre Spatial de Liège), Belgium. The commissioning of the two onboard scientific instruments is currently ongoing; once they are operational, PICASSO will be capable of providing scientific measurements of the Earth’s atmosphere. VISION, proposed by BISA and developed by VTT, will retrieve vertical profiles of ozone and temperature by observing the Earth's atmospheric limb during orbital Sun occultation; and SLP, developed by BISA, will measure in situ plasma density and electron temperature together with the spacecraft potential.

Serving as a groundbreaking proof-of-concept, the PICASSO mission has taught valuable lessons about the advantages of CubeSat technology as well as its many complexities and challenges. These lessons learned, along with preliminary measurements from the two instruments, will be presented and discussed.
The impacts of catastrophic 2019/20 Australian wildfires on erosion and water quality: the case of Sydney’s main water supply
Authors: Doerr Stefan H. , Neris Jonay , Santin Cristina , Lew Roger , Robichaud Peter R. , Elliot William J. , Lewis Sarah A. , Sheridan Gary , Rohlfs Ann-Marie , Ollivier Quinn , Oliveira Lorena
Published: March 2021

The 2019/20 Australian wildfires burned the largest forested area in Australia´s recorded history, with major environmental and socio-economic consequences. These included extensive ash and soil erosion events which threatened water quality in parts on eastern Australia.  

The second largest fire was the 280,000 ha Green Wattle Creek Fire, which burned large forested areas of the Warragamba catchment. This protected catchment provides critical ecosystem services for Lake Burragorang, Australia’s largest urban supply reservoir delivering ~85 % of the water used in Greater Sydney. 

The fire caused major challenges for maintaining the supply of clean water to the Greater Sydney region (> 5 million consumers). Shortly after the fire was contained, an extreme rainfall event (up to ~276 mm in 72 h), caused extensive ash and sediment delivery into the reservoir.

Here we (i) summarise the effects of this unpreceded fire seasons on erosion and water quality in general and (ii) report on the interactions between science and land management to quantify predict and mitigate the risk to water supply for the Greater Sydney region. The latter included assessments of fire severity, ash quantities and their pollutant content using remote sensing and ground measurements, as well as the application and further development of a new modelling tool,  WEPPcloud-Wildfire Ash Transport and Risk tool (WEPPcloud-WATAR - https://wepp.cloud -). This tool allows predicting probabilities for sediment, ash and contaminant transport for different rainfall scenarios, and aided the identification of risk hotspots to focus post-fire erosion mitigation measures.  

Risk modelling, on-ground monitoring and operational mitigation measures ensured the continuity of safe water supply to Greater Sydney. This collaborative interaction between scientists and water managers, that also allowed the refinement of the model capabilities and its outputs, exemplifies the successful outcomes that can be achieved through the close collaboration between science and end-users.   
A dynamically based method for estimating the Atlantic overturning circulation at 26°N from satellite altimetry
Authors: Sanchez-Franks Alejandra , Frajka-Williams Eleanor , Moat Ben , Smeed David
Published: March 2021

The large-scale system of ocean currents that transport warm surface (1000 m) waters northward and return cooler waters southward is known as the Atlantic meridional overturning circulation (AMOC). Variations in the AMOC have significant repercussions for the climate system, hence there is a need for long term monitoring of AMOC fluctuations. Currently the longest record of continuous directly measured AMOC changes is from the RAPID-MOCHA-WBTS programme, initiated in 2004. The RAPID programme, and other mooring programmes, have revolutionised our understanding of large-scale circulation, however, by design they are constrained to measurements at a single latitude.

High global coverage of surface ocean data from satellite altimetry is available since the launch of TOPEX/Poseidon satellite in 1992 and has been shown to provide reliable estimates of surface ocean transports on interannual time scales. Here we show that a direct calculation of ocean circulation from satellite altimetry compares well with transport estimates from the 26°N RAPID array on low frequency (18-month) time scales for the upper mid-ocean transport (UMO; r = 0.75), the Gulf Stream transport through the Florida Straits (r = 0.70), and the AMOC (r = 0.83). The vertical structure of the circulation is also investigated, and it is found that the first baroclinic mode accounts for 83% of the interior geostrophic variability, while remaining variability is explained by the barotropic mode. Finally, the UMO and the AMOC are estimated from historical altimetry data (1993 to 2018) using a dynamically based method that incorporates the vertical structure of the flow. The effective implementation of satellite-based method for monitoring the AMOC at 26°N lays down the starting point for monitoring large-scale circulation at all latitudes.
SQI: Development index and application for two contrasting mediterranean landscapes
Authors: Sillero-Medina Jose Antonio , Hueso-Gonzalez Paloma , Ruiz-Sinoga Jose Damián
Published: March 2021

Soil quality indexes (SQIs) are very useful in assessing the status and edaphic health of soils. This is particularly the case in the Mediterranean area, where successive torrential rainfall episodes give rise to erosion and soil degradation processes; these are being exacerbated by the current climate crisis. The objective of this study was to analyze the soil quality in two contrasting Mediterranean watersheds in the province of Malaga (Spain): the middle and upper watersheds of the Rio Grande (sub-humid conditions) and the Benamargosa River (semi-arid conditions). Field soil sampling was carried out at representative sites, and the soils were subsequently analyzed for various edaphic properties in the laboratory. From the resulting data, the mean values ​​have been grouped and reclassified, and based on a multicriteria evaluation, a SQI for the study region was generated. The results show that there are major differences between the two watersheds, with optimal soil quality values being found in the Rio Grande watershed, but more unfavorable values occurring throughout most of the Benamargosa River watershed.
The Atmospheric Ionization during Substorm Model
Authors: Yakovchuk Olesya , Wissing Jan Maik
Published: March 2021

The Atmospheric Ionization during Substorm Model (AISstorm) is the successor of the Atmospheric Ionization Module Osnabrück (AIMOS) and thus may also be considered as AIMOS 2.0 - AISStorm.

The overall structure was kept mostly unaltered and splits up into an empirical model that determines the 2D precipitating particle flux and a numerical model that determines the ionization profile of single particles. The combination of these two results in a high resolution 3D particle ionization pattern.

The internal structure of the model has been completely revised with the main aspects being: a) an internal magnetic coordinate system, b) including substorms characteristics, c) higher time resolution, d) higher spatial resolution, e) energy specific separate handling of drift loss cone, auroal precipitation and polar cap precipitation, partly even in separate coordinate systems, f) better MLT resolution and g) covering a longer time period. All these tasks have been matched while keeping the output data format identical, allowing easy transition to the new version.