bluuebunny/crossref_metadata_2025 huggingface dataset:
Seismoacoustic signature of the ocean storms at the center of Eurasia
Authors: Smirnov Alexandr , De Carlo Marine , Le Pichon Alexis , Stutzmann Eleonore , Shapiro Nikolai
Published: March 2021

Signature of the ocean storms at the center of Eurasia are studied using data from Kazakhstani stations. Data from seismic and infrasound arrays that are part of the International Monitoring System of the Comprehensive Test Ban Treaty Organization are used, including PS23-Makanchy, AS058-Kurchatov, and IS31-Aktyubinsk. These data were amended with the local information acquired by the National Nuclear Center of Kazakhstan: seismic arrays ABKAR-Akbulak and KKAR-Karatau, and infrasound arrays KURIS-Kurchatov and MKIAR-Makanchy. Seismic and acoustic signals from ocean storms were detected using standardized correlation based method from 2014 to 2017. A seismo-acoustic source model has been developed to predict seismic and acoustic signals. WAVEWATCH3 data are used for the source model simulation. Microbaroms attenuation was calculated using vertical atmospheric profiles developed by the European Centre for Medium-Range Weather Forecasts. Microseism source parameters were corrected for the bathymetry effect. Afterward, actual and predicted microbarom and microseism parameters are compared and analyzed: data are compared between different arrays. The results show clear seasonal features in recorded microseisms and microbaroms indicating that the sources are of the same origin. Discrepancies are found for the predicted and observed microseism backazimuths. The results of this study combining microbarom and microseism observations reveal the strengths and weaknesses of seismic and acoustic methods while analyzing signals from strong storms, and lead to the conclusion that a fusion of two techniques brings qualitatively new results. In particular, it demonstrates its efficiency for locating a source of seismic noise using infrasound observations, predicting the source amplitude using microseismic observations, correcting seismic propagation anomalies due to heterogeneities in the propagation medium using accurate infrasound backazimuths, and inferring new observational constraints in the middle atmosphere using an enhanced description of the microbarom source. These findings are promising for a better description of the source (localization, intensity, spectral distribution) and coupling mechanisms of the ocean/atmosphere/land interfaces.
Modelling losses of reservoir storage capacity from sedimentation in different landscapes 
Authors: Brendel Conrad , Bartosova Alena , Strömqvist Johan , Pers Charlotta , Capell René , Arheimer Berit
Published: March 2021

Reservoir sedimentation represents a significant threat to the reliability of global water and energy supplies. Over the life of a reservoir, storage capacity is gradually lost due to the deposition of sediments. Hydrological models represent a valuable method to study and evaluate the effects of reservoir storage losses on issues such as energy production, discharge capacity, and flood attenuation. The Hydrological Predictions for the Environment (HYPE) model is a semi-distributed, catchment-based hydrology model that has been used to quantify sediment fluxes across a variety of catchment, country, continent, and global modeling domains. In this study, several methods to estimate reservoir storage capacity losses due to sedimentation were added to HYPE, and their impact on sediment simulations and resulting model performance was tested in multiple landscapes in various parts of the world. Selected methods consider the texture and size of deposited sediment particles, the compaction of deposited sediments over time, and the manner in which reservoirs are operated. Results from the study will be used to inform future model development and improve modeling of sediment fluxes at the global scale.
Climate Change – Livelihood – Migration Nexus: A Case Study from Sundarbans, India
Authors: Pramanik Malay , Szabo Sylvia , Pal Indrajit , Udmale Parmeshwar
Published: March 2021

Abstract:

Climate change is one of the most pressing challenges of the 21st century and is likely to increase migration of the marginal communities from the coastal areas throughout the world. It is projected that 200 million people worldwide will be climate refugees by 2050. Owing to high exposure and poor adaptive capacity, low-lying coastal areas and islands in developing countries are the most vulnerable to the impacts of climate change. Therefore, it is imperative to understand how climate change is affecting the livelihoods, in turn, driving the migration in these regions.

The present study focuses on the Sundarbans region located along the coastal belt of West Bengal (India) as a part of Ganga-Brahmaputra mega delta. It is also a home of 4.7 million poor people, who earn below US$10 per month. The region is an exceedingly flat, low-lying, alluvial plain highly exposed to sea level rise, storm surge, tornedoes, cyclonic activity, riverbank erosion, salinization and subsequent mangrove depletion. Due to the climatic hazards, the basic livelihoods are at risk and their strategies towards livelihood collection remains largely unknown. Therefore, the present study provides insights into the nexus among climate stimuli, livelihood risks, and households’ strategies in the region, with special emphasize on climate change.

The study is based on field survey of 150 respondents representing migrant and non-migrant coastal communities from Gosaba, Basanti and Hingalganj block using structured questionnaires. More than 70% of respondents stated that livelihood risks mainly from climate change impacts as the major reason for inter-state migration, which is the main source of income supporting livelihood in the region. This environmental displacement in the Sundarbans region symbolizes the failure of adaptation to mitigate climate change induced sea level rise increasing the exposure to coastal flooding and storm surges, salinization, and erosion.  This study discusses potential mitigation strategies to combat the impacts of climate change on livelihoods of the coastal communities in the region.
Building’s Energy Consumption Pattern and Design-Built Parameters - Influence of Climate on Design Guidelines
Authors: Almufarrej Abdulrahman , Erfani Tohid
Published: March 2021

Increasing buildings energy efficiency is a challenging task. The two main contributing factors that control the overall buildings energy performance are the Heating Ventilation & Air Conditioning (HVAC) system and the building envelope design. Our research investigates how three main building envelop design factors (orientation, compactness and window to wall ratio) impact the overall building’s energy consumption. We focus on typical rectangular shaped buildings and vary the geometry between a square to a rectangular floor plan to provide a basis of energy performance in early stage building design guidance. We test the analysis on building’s energy performance specific to the Middle East’s Kuwait climate condition and environment, and discuss the least energy consumption patterns. This is of importance as most of the electricity consumption in Kuwait are due to HVAC use in residential buildings. The major energy consumption factors are broken down to show how the patterns are unique compared to the previously researched efforts and how a regional set of guidance is of need. The results of this study’s implication on energy and resource use in the Gulf Cooperation Council (GCC) region is discussed, given the high proportion of GHG emission compared to the population within the region.
Hydromorphological monitoring of individual river reaches with UAV-data – image-based measurement of bathymetry and flow velocity
Authors: Eltner Anette , Bertalan László , Lotsari Eliisa
Published: March 2021

Unmanned Aerial Vehicles (UAV) have become a commonly used measurement tool in geomorphology due to their affordable cost, flexibility, and ease of use. They are regularly used in fluvial geomorphology, among other fields, because the high spatiotemporal resolution of UAV data makes it possible to assess the continuum rather than relying on single samples.

In this study, UAV data are used to hydro-morphologically describe three different river reaches of lengths between 150 and 1000 m. Specifically, the surface flow velocity and bathymetry of the rivers were reconstructed. The flow velocities were calculated using the Particle Tracking Velocimetry (PTV) method applied to UAV video sequences. In addition, UAV-based imagery was acquired to perform 3D reconstruction above and below the water surface using SfM (Structure from Motion) photogrammetry, taking into account refraction effects as well as frame processing to increase the visibility of underwater features. Reference data for flow velocities were generated at selected positions using current meters as well as ADCP (Acoustic Doppler Current Profiler) readings. The image-based calculated bathymetry was compared with RTK-GNSS sampling depth measurements and also ADCP data.

The developed workflow enables rapid and regular measurement of hydrological and morphological data of river channels. This ultimately enables multi-temporal assessment and significantly improves hydro-morphodynamic modelling, in particular their calibration.
Shock Acceleration of ~1-100 Kev Electrons at Earth's Bow Shock
Authors: Liu Zixuan , Wang Linghua , Yang Liu , Robert Wimmer-Schweingruber , Shi Quanqi , Stuart Bale
Published: March 2021

We present a statistical study of in-situ shock acceleration of ~1-100 keV solar wind suprathermal electrons at Earth’s bow shock, by using Wind 3D plasma and energetic particle measurements in ambient solar wind and MMS measurements in shock downstream. We pick out 74 shock cases (1 quasi-parallel shock, 73 quasi-perpendicular shocks) during 2015 October - 2017 January, and classify them into 4 types according to their energy spectra in downstream: type 0 (23 cases) without significant electron acceleration after shock passage, type 1 (24 cases) with power-law spectrum, J ∝εβ1_dn, at ~0.8-10 keV, type 2 (16 cases) with power-law-spectrum at ~0.8-10 keV and significant flux enhancement above 30 keV, and type 3 (11 cases) with a clear double-power-law spectrum, J ∝ εβ1_dn (J ∝ εβ2_dn) when ε « εdntr  (ε » εdntr), bending down at εdntr ~20-90 keV. The spectral indexes at lower energies for type 1, type 2 and type 3, β1dn, range from 2.5 to 5, while the spectral indexes at higher energies for type 3, β2dn, range from 4 to 9, and all the spectral indexes have no significant correlation with those in ambient solar wind. Among the 4 types, type 3 is the strongest acceleration with the largest flux enhancement and the lowest β1dn. Besides, we find that the flux ratio between downstream and ambient solar wind Jdn/Jab is field-perpendicular for most cases in both low and high energies, and Jdn/Jab (β1dn) has positive (negative) correlations with θBn and magnetic field compression ratio, rB, which favor the shock drift acceleration (SDA) mechanism. However, Jdn/Jab has no correlation with the drift electric field Ed, while the normalized drift time, Td/Ttr, has a positive correlation with θBn, it suggests that θBn can influence electron drift time and thus influence the acceleration efficiency.
Towards a European denitrification concept for improved groundwater quality management and chemical status assessment
Authors: Gourcy Laurence , Hinsby Klaus , Thorling Laerke , Pinson Stephanie , Ascott Matthew , Broers Hans-Peter , Malcuit Eline , Christophi Christos
Published: March 2021

Denitrification potential is an important parameter to know for adequate and efficient management and assessment of groundwater vulnerability and chemical status. Denitrification removes nitrate in groundwater, but the denitrification capacity is highly variable in space and time, and it may be used up with time. When linking pressure and impact the effect of partial or complete denitrification and denitrification capacity should be taken into account. In some areas, denitrification is seen as an advantage, allowing higher N release below soil without leading to a decrease of the groundwater quality and eventually concentrations in groundwater higher than the WFD and DWD threshold values, which EU member states have to establish to protect drinking water and groundwater dependent terrestrial and associated aquatic ecosystems.    

Within the GEOERA HOVER project, the aim was to assess the spatial extent and importance of denitrification. The studied cases permitted at a first step to highlight the heterogeneities of the approaches due to the variability of information obtained i.e. the likelihood of denitrification, depth and thickness of redox transition zone, complete denitrification status. The parameters used to define the denitrification vary also from one country to another based on a large set of redox sensitive ions (Eh, O2, NO3, NO2, Fe, Mn, SO4, CH4, δ18O-NO3 et δ15N-NO3, H2S or N2). Some of these parameters can be accessed by standard methods in most laboratories, used for groundwater quality monitoring, while others require specialized analysis and interpretations.

Considering groundwater and hydrogeological data available in most of the EU countries, a simple method is proposed in order to classify the monitoring points into three classes: oxic, anoxic and mixed. After being tested in different well-known areas the method will be applied in various lithologies and hydrogeological contexts The proposed method will enable the development of European maps supporting groundwater quality management across Europe.
Explaining recent trends in extreme precipitation in the Southwestern Alps by changes in atmospheric influences 
Authors: Blanchet Juliette , Blanc Antoine , Creutin Jean-Dominique
Published: March 2021

We analyze recent trends in extreme precipitation in the Southwestern Alps and link these trends to changes in the atmospheric influences triggering extremes. We consider a high-resolution precipitation dataset of 1x1 km2 for the period 1958-2017. A robust method of trend estimation is considered, based on nonstationary extreme value distribution and a homogeneous neighborhood approach. The results show contrasting extreme precipitation trends depending on the season. Excluding autumn, the significant trends are mostly negative in the Mediterranean area, while the French Alps show more contrasted trends, in particular in winter with significant increasing extremes in the Western and Southern French Alps and decreasing extremes in the Northern French Alps and Swiss Valais. In autumn, most of Southern France shows significant increasing trends, with up to 100% increase in the 20-year return level between 1958 and 2017, while the Northern French Alps show decreasing extremes.
By comparing these trends to changes in the occurrence of the dominant weather patterns triggering the extremes, we show that part of the significant changes in extremes can be explained by changes in the dominant influences, particularly in the Mediterranean influenced region. We also show that part of the trends in extremes are explained by a shift in the seasonality of maxima. 
Status of GGOS JWG3 on Improved understanding of space weather events and their monitoring
Authors: Garcia-Rigo Alberto , Soja Benedikt ,   "GGOS's JWG3 - Improved understanding of space weather events and their monitoring" team
Published: March 2021

The JWG3 aims at investigating different approaches to monitor space weather events using the data from different space geodetic techniques and, in particular, combinations thereof. Simulations will also be considered since these could be beneficial to identify the contribution of different techniques and prepare for the analysis of real data. Different strategies for the combination of data are also to be investigated, in particular the weighting of estimates from different techniques in order to increase the performance and reliability of the combined estimates.

Furthermore, existing algorithms for the detection and prediction of space weather events shall be explored and improved to the extent possible. Additionally, the geodetic measurement of the ionospheric electron density will be complemented by direct observations from the Sun gathered from existing spacecraft, such as SOHO, ACE, SDO, Parker Solar Probe, among others. The combination and joint evaluation of multiple datasets from different space geodetic observation techniques (e.g., geodetic VLBI) is still a great challenge. In addition, other indications for solar activity - such as the F10.7 index on solar radio flux, SOLERA as EUV proxy or rate of Global Electron Content (dGEC), provide additional opportunities for comparisons and validation.

As per JWG3 objectives, these include the identification of the key parameters useful to improve real time/prediction of ionospheric/plasmaspheric VTEC, Ne estimates, as well as ionospheric perturbations, in case of extreme solar weather conditions. In general, we are on the way to gain a better understanding of space weather events and their effect on Earth’s atmosphere and near-Earth environment.
Sea Level Anomalies in the Southern Ocean due to Thermohaline Variability
Authors: Roquet Fabien , Kolbe Marlen , Pauthenet Etienne , Nerini David
Published: March 2021

The Southern Ocean is responsible for the majority of the global oceanic heat uptake which contributes to global sea level rise. At the same time, ocean temperature does not change everywhere at the same rate and salinity changes are also associated with sea level variability. Changes in heat and salt content drive together variations in the steric height that differ importantly in both time and space. This study investigates steric height variability in the Southern Ocean from 2008 to 2017 by analysing temperature and salinity variations obtained from global ocean reanalyses. The thermohaline variability is decomposed on so-called thermohaline modes using a functional Principal Component Analysis (fPCA). Thermohaline modes provide a natural basis on which to decompose the joint temperature-salinity vertical profiles into a sum of vertical modes weighted by their respective principal components. Steric height was computed in the reanalyses and related to the principal component using a Multiple Linear Regression (MLR) model. Trends in steric height are found to differ significantly between subtropical and subpolar regions, simultaneously which with a shift from a thermohaline stratification dominated by the first "thermocline" mode in the North to the second "saline" mode in the South. The Polar Front appears as a natural boundary between the two regions, where steric height variations are minimized. Since 2008, steric height has dropped close to the Antarctic continent, while subtropical waters farther north have mostly risen due to increased heat storage. While the dominant cause for the significant sea level rise south of 30S remains freshwater discharge from glaciers and ice sheets, thermohaline variability produces sizeable regional variability in the rate of sea level rise.
Holocene sea-ice dynamics in Petermann Fjord 
Authors: Detlef Henrieka , Reilly Brendan , Jennings Anne , Mørk jensen Mads , O'Regan Matt , Glasius Marianne , Olsen Jesper , Jakobsson Martin , Pearce Christof
Published: March 2021

Today Nares Strait is covered by sea ice for 11 months per year. The seasonal sea-ice regime and formation of landfast ice depend on the development of ice arches. Historically a northern and southern ice arch have been observed in Robeson Channel and Smith Sound, respectively, with only the southern arch leading to a complete freeze up of the strait. In recent decades, the northern arch has become more prominent, indicating a regime shift in Nares Strait sea-ice dynamics with important consequences for the export of ice from the Lincoln Sea, the regional oceanography, and the ecosystem related to the annual opening of the North Water Polynya lee of the southern ice arch. Modelling studies suggest a link between mobile sea ice and enhanced Ekman transport of modified Atlantic Water to Greenland fjord systems bordering Nares Strait. Further, a reduction in the fjords’ fast ice season, in response to Nares Strait sea-ice dynamics, might decrease its buttressing effect on the marine-terminating outlet glaciers in northern Greenland. One such glacier is Petermann Glacier, draining 4% of the Greenland Ice Sheet and terminating in a 48 km long ice tongue in Petermann Fjord.

The Petermann 2015 Expedition to Petermann Fjord and adjacent Hall Basin recovered a transect of cores from Nares Strait to under the 48 km long ice tongue of Petermann glacier. First results suggest that no ice tongue existed in Petermann Fjord for large parts of the Holocene, raising the question of the role of the ocean and the marine cryosphere in the collapse and re-establishment of the ice tongue. We present a multi-proxy study (sea-ice related biomarkers, total organic carbon and its carbon isotopic composition, and benthic and planktonic foraminiferal abundances) exploring the Holocene sea-ice dynamics at site OD1507-03TC-41GC-03PC in outer Petermann Fjord. Our results are in line with a tight coupling of the marine and terrestrial cryosphere in this region and, in connection with other regional sea-ice reconstructions, give insights into the Holocene evolution of ice arches and associated landfast ice in Nares Strait.
Lithospheric structure of the North American Craton constrained by full waveform inversion
Authors: Zhou Tong , Chen Min , Xi Ziyi , Li Jiaqi
Published: March 2021

Cratonic lithosphere is believed to be rigid and less deformed during a long period of time. However, the detailed structure of Cratons may bring information of the complex formation and assemblage process of the continental lithosphere. Here, we present the seismic radial anisotropic structure of the North American Craton (NAC) constrained by a regional full-waveform inversion (FWI) with 465,422 high-quality frequency-dependent travel time misfit measurements with the shortest period of 15 s from both the body wave and surface wave recordings of 5,120 stations and 160 earthquakes located in the contiguous U.S and surrounding regions. Started from an initial model constructed by combining US.2016 and Crust1.0 in the crust and S40RTS (isotropic) in the mantle, we are able to have the optimized crustal structure in terms of initial waveform similarity and get rid of existing features from other radially anisotropic mantle models.

Our new model reveals the NAC lithosphere with about +2% voigt shear wave speed anomaly and an average thickness of 200–250 km beneath the Superior Craton, and becomes thinner towards the eastern, the southern, and the southwestern margins with a thickness decreased to 100–150 km. The radial anisotropy manifests a layer of higher horizontal shear wave speed VSH (ξ=VSH2/VSV2>1) beneath the core of Superior Craton down to around 160 km, where the higher vertical shear wave speed VSV (ξ<1) is observed beneath 160 km. Such radial anisotropy layering is also observed in the margin of continental lithosphere but with shallower depth. The radial anisotropic layer matches the receiver function results of mid-lithosphere discontinuities of the Craton cores, and the lithosphere conductivity result. The radial anisotropy layering observation confirms the two-layered lithosphere structure of the NAC, where the upper layer likely represents the original radial anisotropy fabric related to the cooling of the craton core, while the lower layer might be related to the tectonic processes more recently, e.g., accretion . The lithospheric thinning beneath the NAC margins indicates the deformation of the lithosphere and is likely controlled by the large-scale mantle convection, therefore relates to the further modification process of the NAC.
Practical tool for drought characteristics calculation
Authors: Mottaghi Zadeh Mahyar , Habibi Maral
Published: March 2021

There are many ways to identify and monitor drought conditions. Scarcely are tools that calculate drought characteristics, The "SDF Calculator" works to bring monitoring tools to the public so they can assess drought conditions, this tool is used to assess and identify drought and its intensity.

Drought severity refers to the absolute sum of consecutive SDI values below a given threshold level while drought duration is the number of consecutive months that SDI is below that threshold, and drought frequency is a number of months with drought condition (means SPI < -0.5 or any given threshold that is desire, the threshold of drought index is a value that an index faces to drought condition. In every index, this value can be changed. For example, in many indices, the threshold of drought starts from zero or less zero. In other words, when the value of an index is calculating then all the values located in the drought classes, refer to the severity of the drought.

Droughts and exceptionally wet periods are regional phenomena, which are considered as major environmental extremes, especially in semiarid regions of the world. The development of severity-duration-frequency (SDF) relationships of droughts and wet periods is important in hydrological and climatic plannings in any country.

In this study, we aimed to offer a novel software model to be used for a quantitative description of droughts and wet periods to provide an overview of drought intensity and analyzing their severity, frequency, and duration. In addition, we have been able to develop a state-of-the-art bespoke software application, so the users are able to analyze drought based on the regional thresholds. While most of the analysis applications have used programming languages such as R or Python, due to the lack of software libraries in the .NET development environment, we have managed to offer our development environment based on .NET Core and C# programming language. The software application accepts inputs from various file formats or APIs, processes the data, and demonstrates the outcome in different graphs and maps depending on the geographical location of study areas. The outputs are not only can be exported as different formats to be used in big data applications but also might be exposed as web APIs to be used in live applications.

 

 Keywords: Drought characteristics, SDF Calculator, API, Standardized Drought Indices (SDI)
Optimal estimation of snow and ice surface parameters from imaging spectroscopy measurements
Authors: Bohn Niklas , Thompson David , Carmon Nimrod , Susiluoto Jouni , Turmon Michael , Helmlinger Mark , Green Robert , Cook Joseph , Guanter Luis
Published: March 2021

Snow and ice melt processes are key variables in Earth energy-balance and hydrological modeling. Their quantification facilitates predictions of meltwater runoff and distribution and availability of fresh water. Furthermore, they are indicators of climate change and control the balance of the Earth's ice sheets. These processes decrease the surface reflectance with unique spectral patterns due to the accumulation of liquid water and light absorbing particles (LAP), making imaging spectroscopy a powerful tool to measure and map this phenomenon. Here we present a new method to retrieve snow grain size, liquid water fraction, and LAP mass mixing ratio from airborne and space borne imaging spectroscopy acquisitions. This methodology is based on a simultaneous retrieval of atmospheric and surface parameters using optimal estimation (OE), a retrieval technique which leverages prior knowledge and measurement noise in the inversion and also produces uncertainty estimates. We exploit statistical relationships between surface reflectance spectra and snow and ice properties to estimate their most probable quantities given the reflectance. To test this new algorithm we conducted a sensitivity analysis based on simulated top-of-atmosphere radiance spectra using the upcoming EnMAP orbital imaging spectroscopy mission, demonstrating an accurate estimation performance of snow and ice surface properties. An additional validation experiment using in-situ measurements of glacier algae mass mixing ratio and surface reflectance from the Greenland Ice Sheet yields promising results. Finally, we evaluated the retrieval capacity for all snow and ice properties with an AVIRIS-NG acquisition from the Greenland Ice Sheet demonstrating this approach’s potential and suitability for upcoming orbital imaging spectroscopy missions.
Seasonal impact of biogenic very short-lived bromocarbons on lowermost stratospheric ozone between 60◦ N and 60◦ S during the 21st century
Authors: Barrera Javier , Fernandez Rafael , Iglesias-Suarez Fernando , Cuevas Carlos A. , Lamarque Jean-Francois , Saiz-Lopez Alfonso
Published: March 2021

Biogenic very short-lived bromocarbons (VSLBr) currently represent ∼25 % of the total stratospheric bromine loading. Owing to their much shorter lifetime compared to anthropogenic long-lived bromine (e.g. halons) and chlorine (e.g. chlorofluorocarbons), the impact of VSLBr on ozone peaks in the lowermost stratosphere, which is a key climatic and radiative atmospheric region. Here we present a modelling study of the evolution of stratospheric ozone and its chemical loss within the tropics and at mid-latitudes during the 21st century. Two different experiments are explored: considering and neglecting the additional stratospheric injection of 5 ppt biogenic bromine naturally released from the ocean. Our analysis shows that the inclusion of VSLBr results in a realistic stratospheric bromine loading and improves the agreement between the model and satellite observations of the total ozone column (TOC) for the 1980–2015 period at mid-latitudes. We show that the overall ozone response to VSLBr at mid-latitudes follows the stratospheric evolution of long-lived inorganic chlorine and bromine throughout the 21st century. Moreover, the seasonal VSLBr impact on lowermost stratospheric ozone at mid-latitude is influenced by the seasonality of the heterogeneous inorganic-chlorine reactivation processes on ice crystals. Indeed, due to the more efficient reactivation of chlorine reservoirs (mainly ClONO2 and HCl) within the colder SH-ML lowermost stratosphere, the seasonal VSLBr impact shows a small but persistent hemispheric asymmetry through the whole modelled period. We conclude that the link between biogenic bromine sources and seasonal changes in heterogeneous chlorine reactivation is a key feature for future projections of mid-latitude lowermost stratospheric ozone during the 21st century.
Turbulence properties in coupled and decoupled stratocumulus-topped boundary layers
Authors: Nowak Jakub , Siebert Holger , Szodry Kai , Malinowski Szymon
Published: March 2021

In marine atmospheric boundary layer (MBL), turbulence plays an important role in vertical transport of mass, heat and moisture, which is crucial for the emergence and evolution of stratocumulus clouds. We use high resolution in situ measurements of flow velocity, temperature, humidity and liquid water content performed from the helicopter-borne platform ACTOS in the region of Eastern North Atlantic in the course of  ACORES campaign to compare turbulence properties in coupled and decoupled stratocumulus-topped boundary layer. Derived parameters include turbulence kinetic energy, its production and dissipation rates, anisotropy of the inertial range, turbulent fluxes of sensible and latent heat as well as characteristic lengthscales.

Inside the observed coupled MBL, turbulence is intensively produced by buoyancy at the cloud top and at the surface, and dissipated with equal rate across the entire layer depth. Turbulence is close to isotropic and inertial range exhibits scaling relatively close to that predicted by Kolmogorov theory. Inside the decoupled MBL properties of turbulence in the bottom sub-layer (BSL) vary from those in the cloud and sub-cloud layers, which together form upper sub-layer (USL). Transition in between the BSL and the USL is most pronounced in the gradient of specific humidity. The USL is characterized by weak buoyancy production in the cloud, strong anisotropy of turbulence and the scaling deviating from that predicted by Kolmogorov theory. In BSL, fluxes of buoyancy and latent heat decrease with height from the maximum at the surface down to about zero at the transition.

In general, results are consistent with the conceptual explanation of decoupling mechanism involving two separated zones of circulation and mixing: surface driven and cloud top driven. Our observations suggest that contrasting turbulence parameters need to be considered together with convection organization in order to properly quantify the vertical transport between ocean surface and stratocumulus cloud.
Recent updates to the atmospheric aerosol modelling of the ECMWF IFS in support to CAMS
Authors: Remy Samuel , Kipling Zak , Huijnen Vincent , Flemming Johannes , Metzger Swen , Engelen Richard
Published: March 2021

The Integrated Forecasting System (IFS) of ECMWF is used within the Copernicus Atmosphere Monitoring Service (CAMS) to provide global analyses and forecasts of atmospheric composition, including aerosols as well as reactive trace gases and greenhouse gases.

The aerosol model of the IFS, IFS-AER, is a simple sectional-bulk scheme that forecasts seven species:  dust, sea-salt, black carbon, organic matter, sulfate, and  since July 2019, nitrate and ammonium.  The main developments that have been recently carried out, tested and are now contemplated for implementation in the next operational version (known as cycle 48r1) are presented here.

The dry deposition velocities are computed as a function of roughness length, particle size and surface friction velocity, while wet deposition depends mainly on the precipitation fluxes. The parameterizations of both dry and wet deposition have been upgraded with more recent schemes, which have been shown to improve the simulated deposition fluxes for several aerosol species. The impact of this upgrade on the skill scores of simulated aerosol optical depth (AOD) and surface particulate matter concentrations against a range of observations is very positive.

The simulated surface concentration of nitrate and ammonium are frequently strongly overestimated over Europe and the  United States in the current version of the IFS. Nitrate, ammonium, and their precursors nitric acid and ammonia, were evaluated against a range of ground and remote data and it was found that the recently-implemented gas-particle partitioning scheme is too efficient in producing nitrate and ammonium particles.

A series of small-scale changes, such as adjusting nitrate dry deposition velocity, direct particulate sulphate emission, and limiting nitrate/ammonium production by the concentration of mineral cations, have been implemented and shown to be effective in improving the simulated surface concentration of  nitrate and ammonium.

The representation of secondary organic aerosol (SOA) in the IFS has been overhauled with the introduction of a new SOA species, distinct from primary organic matter, with anthropogenic and biogenic components. The implementation of this new species leads to a significant improvement of the simulated surface concentration of organic carbon. An evaluation of simulated SOA concentrations at the surface against climatological values derived from observations using Positive Matrix Factorisation (PMF) techniques also shows a reasonable agreement.
Modeling of coupled flow, transport and biogeochemical reactions during electrokinetic bioremediation: model development and application
Authors: Sprocati Riccardo , Rolle Massimo
Published: March 2021

Electrokinetic (EK) remediation is one of the few in-situ remediation technologies that can effectively remove contaminants from low-permeability porous media. Process-based modeling, including the complex multiphysics and biogeochemical processes occurring during electrokinetic remediation, is instrumental to describe EK systems and to assist in their design. In this work we use NP-Phreeqc-EK [1], a multidimensional, multiphysics code which couples a flow and transport simulator (COMSOL Multiphysics) with a geochemical code (PhreeqcRM) through a MATLAB LiveLink interface. The model allows the simulation of coupled fluid flow, solute transport, charge interactions and biogeochemical reactions during electrokinetics in saturated porous media. The process-based code is applied for the modeling of electrokinetic delivery of amendments to enhance bioremediation (EK-Bio) of chlorinated compounds at a pilot test site [2]. We simulate both conservative and reactive transport scenarios and we compute and show the Nernst-Planck fluxes and the velocities of the different species (such as lactate, chlorinated ethenes and degrading microorganisms). To compare remediation performances and model outcomes we define different metrics quantifying the spatial distribution of the delivered reactants and the mass of the organic contaminants in the system. The process-based model allowed the simulation of the key processes occurring during EK-Bio, including 1) multidimensional electrokinetic transport such as electromigration of charged species and electroosmosis, 2) Coulombic interactions between ions in solution, 3) kinetics of contaminant biodegradation, 4) dynamics of microbial populations, 5) mass transfer limitations and 6) geochemical reactions.

 

[1] Sprocati, R., Masi, M., Muniruzzaman, M., & Rolle, M. (2019). Modeling electrokinetic transport and biogeochemical reactions in porous media: A multidimensional Nernst–Planck–Poisson approach with PHREEQC coupling. Advances in Water Resources, 127, 134-147.

[2] Sprocati, R., Flyvbjerg, J., Tuxen, N., & Rolle, M. (2020). Process-based modeling of electrokinetic-enhanced bioremediation of chlorinated ethenes. Journal of Hazardous Materials, 397, 122787.
Controlled drainage in future climate scenarios
Authors: Salla Aleksi , Salo Heidi , Koivusalo Harri
Published: March 2021

Climate change is projected to result in higher temperatures, higher annual precipitation and more uneven distribution of precipitation in the northern regions. This requires adaptation in agriculture where both excessively wet and dry cycles pose challenges to cropping. Until now, water management in northern agricultural fields has been resting primarily on efficient drainage, but interest towards more flexible measures has increased.

This study focuses on the hydrological effects of climate change and controlled drainage operated with subsurface drains and an open collector ditch in an agricultural field. The objective was to computationally estimate how groundwater levels and water balance respond to controlled drainage and open ditch scenarios in climate conditions projected to take place in Finland during this century. A hydrological model FLUSH was used to simulate the hydrology of an experimental field in Sievi, Northern Ostrobothnia, Finland during years 1970–2100. Down-scaled climate projections from EURO-CORDEX (RCP 8.5 and RCP 2.6) were used as meteorological input. The temporal development of the field hydrology and the effects of controlled drainage were examined by dividing the time series into four subsequent time intervals (historical period and three future periods).

Two different control scenarios were studied. Drainage intensity was reduced during growing seasons in summers (Jun.–Aug.) and either in autumn (Oct.–Nov.) or from autumn to spring (Oct.–Mar.). During these periods, groundwater table was on average 17–29 cm, 28–30 cm and 36–40 cm higher, respectively, in the control scenarios when compared to conventional subsurface drainage in different study intervals and emission scenarios. The implementation of controlled drainage reduced annual drain discharge by 21–46 mm. The projected temporal evolution of the effects of controlled drainage on groundwater levels and annual drain discharges were not monotonous, but the projected effects were larger during the future periods when compared to the historical period. Controlled drainage effect on groundwater levels was seen during both dry and wet years. Controlled drainage was assessed to be an effective method to control field water processes currently and in the future decades. The open collector ditch lowered groundwater levels within a distance of 115 m from the ditch.
Shallow Imaging of Gas and Hydrate Using the Deep-towed ACS Data in Joetsu Basin, Niigata, Japan
Authors: Hutapea Fernando , Tsuji Takeshi , Katou Masafumi , Asakawa Eiichi
Published: March 2021

The deep-towed Autonomous Continuous Seismic (ACS) is a deep-towed marine seismic acquisition method. The ACS utilizes high frequency seismic source (ranging from 700 Hz to 2300 Hz) and multi-channel receivers that both source and receivers can be located close the seafloor. Moreover, the ACS is suitable to obtain high-resolution image of shallow geological structures. Since ACS data acquisition can be operated near the seafloor, the ocean (strong) current makes the position of both receivers and sources irregular (unstable) and it is hard to measure the absolute depth of both receivers and sources. During data processing, the unstable depth of both sources and receivers not only make the recorded seismic reflection curve (hyperbolic curve) rugged, but also makes the velocity analysis process more difficult because the velocity semblance is not clear. In this study, we propose a processing scheme to solve the unstable source–receiver position problem and thus to construct an accurate final stack profile (Hutapea et al., 2020 doi:10.1016/j.jngse.2020.103573). We used deep-towed ACS data acquired in the Joetsu Basin in Niigata, Japan, where hydrocarbon features in the form of gas chimneys, gas hydrate, and free gas have been observed. Furthermore, sidelobes in the ACS source signature defocus the source wavelet and decrease the bandwidth frequency content. We designed a filter to focus the source signature. Our proposed approach considerably improved the quality of bandwidth frequency of the source signature and the final stacked profile. Even though depth information was not available for all receivers, the velocity semblance was well focused. Our seismic attribute analyses for the final stack section shows that free gas accumulations are characterized by low reflection amplitude and an unstable frequency component, and that hydrate close to the seafloor can be identified by its high reflection amplitude.
A high-resolution seismic survey across the Balmuccia Peridotite, Ivrea Zone, Italy - Project DIVE phase two, site investigation
Authors: Pasiecznik Damian , Greenwood Andrew , Ludovic Baron , Florian Bleibinhaus , György Hetényi
Published: March 2021

The Ivrea Verbano Zone (IVZ) is one of the most complete crust–upper mantle geological references in the world, and the Drilling the Ivrea-Verbano zone project (DIVE) aims to unravel the uncertainties below this area. Geophysical anomalies detected across the IVZ indicate that dense, mantle-like rocks are located at depths as shallow as ca. 3km. Thus, several geological, geochemical and geophysical studies are planned, including the drilling of a 4km deep borehole that will penetrate the Balmuccia Peridotite (Val Sesia, Italy) to approach and possibly cross the crust–mantle transition zone, and provide, for the first time, geophysical in-situ measurements of the IVZ.

One of the primary requirements before drilling is a seismic site characterization, to define with precision the correct positioning and orientation of the borehole, to assess potential drilling hazards and to allow for the spatial extrapolation of the borehole logs. For that goal, two joint geophysical surveys were performed in October 2020 in a collaboration of GFZ Potsdam, Université de Lausanne and Montanuniversität Leoben. First: a deep seismic survey, entitled SEIZE (SEismic imaging of the Ivrea ZonE), consisting of two approximately 15km-long seismic lines performed by GFZ Potsdam, that aim to resolve the deeper structure of the IVZ in the area, and second: a static seismic survey at the proposed drill site, entitled HiSEIZE (High-resolution SEismic imaging of the Ivrea ZonE), geared towards providing high-resolution seismic images of the uppermost few km at the proposed drill site.

The HiSEIZE survey, the subject of this study, was performed with a fixed spread of 200 vertical geophones and 160 3C-sensors, spaced at ca. 11m along three sub-parallel lines spaced 50-80m apart. Vibroseis source points were at 22m stations along a 2.4km line utilizing a high-frequency (12-140 Hz) 10s linear sweep with 3s listening time. In addition to this, the HiSEIZE receiver spread was active during the deep SEIZE survey, information that may be useful in determination of a velocity model through the Balmuccia Peridotite.

This project will not only provide site characterization for the DIVE project, but also contribute to understanding the structure of the Balmuccia Peridotite, its changes in depth and its relationship with the crustal-mantle transition.

Here we present the data and discuss the challenges of 3D pre-stack-imaging in an area of extreme topography.
Petrophysical study of different rock types from the mining area of Freiberg, Germany
Authors: Graffmann Leonie , Sonntag Martin , Börner Jana
Published: March 2021

The ore mining area of Freiberg is located in the federal state of Saxony in the east part of Germany and is characterized by hydrothermal ore mineralization.

The present petrophysical study concentrates on three different rock types from the research mine “Reiche Zeche”. The set of samples contains rocks from the metamorphic host rock - Freiberger Gneiss (FG), from a hydrothermal alternated gneiss (hG) and from a pyrit-galenit rich ore vein (ore). The investigations include the determination of density and porosity as well as laboratory measurements of the Spectral Induced Polarization (SIP) in the frequency range from 10-3 to 104 Hz. Furthermore, measurements of the magnetic susceptibility and P-wave velocity were performed.

For the determination of P-wave velocity by ultrasonic measurements, the rock samples were cut into cubes (5 cm x 5 cm) under preservation of their spatial orientation. The sample set contains 17 cubes (FG - 8 cubes, hG -3 cubes and ore – 6 cubes).

The determination of the complex resistivity was performed in a SIP – measuring cell on cylindric plugs with a length of 3 cm and a diameter of 2 cm. For the SIP-measurements 19 plugs (FG – 11 plugs, hG – 2 plugs and ore – 6 plugs) were available.

Density and magnetic susceptibility measurements were performed on 10 samples of crushed material for each rock type.

The data sets of complex resistivity and P-wave velocity measurements from rock samples of the metamorphic host rock and the ore vein were analysed with focus on possible anisotropic behaviour.
Water exchange and renewal times of a micro-tidal fjord in isohaline coordinates
Authors: Lange Xaver , Jochum Markus
Published: March 2021

In micro-tidal coastal systems, the hydrodynamics in fjords reduce to a competition between horizontal density gradient, friction and wind stress. Depending on the depth of the entrance sill, the importance of these factors for water exchange varies within the vertical layer structure of fjords. This study investigates these renewals of water bodies in an isohaline framework, using the example of the Gullmar Fjord on the west coast of Sweden, a transitional area between the brackish Baltic Sea and the northeastern region of the North Sea.

To estimate the influence of wind and baroclinic pumping on volume and salinity transport and their importance on the exchange time scales, a well-validated, realistic, and highly resolved 3D coastal ocean model (GETM) is used, calibrated with especially designed observations. Simulations were combined with passive numerical tracers and evaluated with the mathematical analysis framework of the Total Exhange Flow (TEF).

The results highlight the advantage of isohaline coordinates in the study of water mass transformations within the fjord, compared to geographic coordinates, and the high sensitivity of the exchange flow to sub-grid turbulence.