bluuebunny/crossref_metadata_2025 huggingface dataset:
Revisiting the solar-interplanetary connection of the early August 1972 solar storms
Authors: Cid Consuelo , Saiz Elena , Flores-Soriano Manuel
Published: March 2022

The solar storms happened in early August 1972 have been recently described as an example of a space weather event due to its technological impacts. Besides the interest of this event for the space weather community, these storms were extensively analyzed by the scientific community in 1970s and 80s due to their relevance considering the enhanced levels of solar activity and also their interplanetary consequences. The passage of several interplanetary shocks was observed in Pioneers 9 and 10 data and also in Pognoz-1, Prognoz-2 and HEOS-2 data, making this event particularly suitable for the study of the evolution of the solar ejections in the Heliosphere. This work starts reviewing the papers on the interplanetary scenario during this event. Then, we revisit their conclusions considering the scientific advances since that date and finally go ahead in the analysis of the event. 
Enhanced meltwater discharge and water mass evolution in Southwest Greenland since the end of the Little Ice Age
Authors: Sun Yun-Ju , Robinson Laura , Parkinson Ian , Stewart Joseph , de Carvalho Ferreira Maria Luiza , Hendry Katharine
Published: March 2022

The Arctic region is noted to be sensitive in its response to anthropogenic warming. The Greenland Ice Sheet is experiencing accelerated mass loss via surface melting and ice discharge. This freshwater input is likely to influence global heat distribution via the Atlantic Meridional Overturning Circulation (AMOC). To better understand past natural variations in this system, proxy reconstructions are required to give a longer-term perspective. Previous proxy studies have suggested that human-induced AMOC slowdown began as early as the nineteenth century. However, the lack of high temporal resolution data from the last millennium means that the role of meltwater discharge on the evolution of North Atlantic intermediate waters, especially during the Little Ice Age (LIA), remains unclear.

Here, we present both weathering and temperature records from deep-sea scleractinian corals collected from Southwest Greenland (Nuuk Trough). We analysed 234U/238U, rare earth elements with yttrium (REEY) and trace elements (Li/Mg temperature proxy) along with precise U-Th dating of corals. Samples were from 750 m and 1200 m water depth with ages spanning the last 1000 years. The study site is influenced by surface meltwater from the West Greenland Ice Sheet. It is also at the convergence point of shallow cold Arctic-sourced water and deeper warm Atlantic-sourced water, providing an ideal location for tracing AMOC variations.

Our coral data show West Greenland seawater δ234U has increased ~2‰ toward modern seawater value since the end of the LIA (1700 C.E.), suggesting an increase in subglacial physical weathering input. This is supported by our terrestrial discharge record from REEY data that indicates an increase in meltwater discharge since the end of the LIA. The temperature record shows a gradual cooling trend from 1600 to 1900 C.E. at 1200 m depth, followed by warming at 750m. We suggest that the temperature drop at intermediate depth is linked to a change in water mass structure, as the thermocline shallowed and colder, deeper waters expanded. Cooling at this depth is consistent with a weakened AMOC, with less penetration of warm Atlantic waters. Our findings highlight the complex interactions between glacial meltwater and intermediate water circulation in the last millennium.
Validation of a New Version of the WindCube Scan Lidar 
Authors: Benzo Cristina , Thobois Ludovic
Published: March 2022

Accurate measurement of the wind is essential in many applications. From improving the efficiency of wind farms to identifying wind hazards at ports, airports, or industrial plants, precise knowledge of the wind is critical. Wind Lidars are widely used to provide detailed information on wind, and Scanning Wind Lidars provide further measurements in full hemisphere around its location with multiple scanning patterns (azimuthal scans, elevation scans, etc.).

User feedback has always played a vital role in developing this technology. In the most recent round of development, two key areas were identified for improvement, resulting in the development of a new version of the WindCube Scan:

Reducing range ambiguities that occur when clouds or obstacles are located further than the maximum acquisition distance.

Adding more flexibility between the different modes of measurement to optimize both measurement range and resolution.

The new WindCube Scan addresses these points with the introduction of new resolutions, mitigated ambiguities, and greater ranges.

This paper will describe the metrological validation performed over the last year both in the field and in a factory setting.

A field validation was conducted in collaboration with two leading meteorological organizations in Europe, pioneers in the PROBE European project for large-scale atmospheric boundary layer remote-sensing deployment and data-sharing. Both organizations received the new version of WindCube Scan for a beta test. They gathered wind data at their sites and compared to other remote sensing devices such as radiosondes and radar wind profilers to verify the performances of different resolutions and overall performance of data retrieval and wind speed precision.

A factory validation, which was conducted at the Vaisala France site, near Paris, consisted of both an indoor and outdoor test. The indoor verification test was aimed at testing radial wind speed precision with intrinsic lidar parameters such as pulse shape, energy, etc. The outdoor validation followed guidelines set by the ISO 28902-2 regarding remote sensing measurement verification with other in-situ devices. The lidar was pointed to an ultrasonic anemometer on a meteorological tower about 2km away. The wind speed measurements from both devices were then compared for precision and accuracy with proper filtering of unsuitable weather conditions. 

The results of the validation testing thus far show positive performance and noticeable improvements of the new version of the WindCube Scan. Additionally, the external validation collaboration with other PROBE members highlights the importance of fortifying and understanding remote sensing device precision and data collection methods if they are to be integrated into large, observational networks.
Groundwater salinization dynamics - a conceptual modeling approach to prioritize water management plans in a changing environment
Authors: Külls Christoph , Bassukas Dimitrios
Published: March 2022

Groundwater salinization has been a phenomenon of increasing concern in the circum-Mediterranean region. Future hydroclimatic and social changes in the area are expected to affect the dynamics of salinization, and to create further pressure on water resources. However, these dynamics are system-specific. To effectively mitigate predicted impacts, local water management needs to prioritize actions based on the temporal dynamics of the change. The conceptual modeling approach BC2C has been applied to the coastal aquifer on the island of Samos, Greece. The approach takes into account the flow dynamics, depending on physical parameters of the flow system, and connects biogeophysical changes of the land-use system to a response function of aquifer salinity. This straightforward modeling approach based on analytical functions yields a time-impact relationship of propagation and recession for given interventions. At the MEDSAL project pilot site of the Kampos plain in Samos, the BC2C model generates a response time between 15 years for the shallow aquifer and up to 150 years for the coupled deep aquifer system. This insight into the dynamics of groundwater salinization can be used as a guide and baseline for future groundwater management plans, and highlights the importance of a medium to long-term perspective. 
Summer Arctic temperatures in PMIP4 Last Interglacial simulations and their link to Arctic sea ice
Authors: Sivankutty Rahul , Sime Louise , Malmierca Vallet Irene , de Boer Agatha
Published: March 2022

Investigating climate models responses and feedbacks under warmer climates is useful in building confidence in future climate projections. Here we focus on the summer sea ice in the Arctic during the Last Interglacial period (LIG), when the Arctic was warmer than the Pre-Industrial period (PI) by around 4.5 ± 1.7 K. Given that it is difficult to ascertain the state of Arctic sea ice from marine core proxies of sea ice state, we focus instead on summer surface air temperature (SSAT) in CMIP6-PMIP4 simulations and compare these with equivalent proxy data. All 12 models we have analysed show both warmer SSAT and a reduction in summer sea ice in the LIG compared to the PI, with an average warming of +3.6K and an average 52% decrease in minimum sea ice area.

 

We find that model-observation differences in LIG SSAT are linearly related to the percentage loss of summer Arctic sea ice. However this general finding does not fit the CNRM model result, which is an outlier. This simulation captures the observed pattern of SSAT, without being close to ice-free. However peculiarities in the CNRM set-up (forcing and sea ice model tuning) means it is unclear what can be drawn from this one result. CNRM aside, models tend to yield more accurate LIG SSAT changes when they are closer to an ice-free state in summer. The models which feature sea ice losses larger than the multi-model-mean sea ice loss, tend to have the smallest model-observation SSAT errors. The results of this study provides caveated support to the argument that Arctic could have been ice-free during LIG summers. That said, a careful examination of the SSAT dataset would also be value to the LIG community, given that these results are dependent on the LIG SSAT observational dataset.

 
Ocean climate indices and Total Solar Irradiance: causality over the past few decades and revision of indices uncertainties 
Authors: Skakun Aleksandra , Volobuev Dmitry
Published: March 2022

Pearson’s correlation is usually used as a criterion for the presence or absence of a relationship between time series, but it is not always indicative for nonlinear systems like climate. Therefore, we implement one of the methods of nonlinear dynamics to detect connections in the Sun-climate system. Here we estimate the causal relationship between Total Solar Irradiance (TSI) and Ocean climate indices over the past few decades using the method of conditional dispersions (Cenys et al., 1991). We use a conceptual ocean-atmosphere model (Jin, 1997) with TSI added as a forcing to calibrate the method. We show that the method provides expected results for connection between TSI and the model temperature. Premixing of Gaussian noise to model data leads to decrease of detectable causality with increase of noise amplitude, and the similar effect occurs in empirical data. Moreover, in the case of the empirical data, we show that the method can be used to independently estimate uncertainties of Ocean climate indices.
Gravimetric investigation of the structure of the Etna summit craters system
Authors: Zahorec Pavol , Papčo Juraj , Greco Filippo , Messina Alfio , Pánisová Jaroslava , Vajda Peter , Carbone Daniele
Published: March 2022

New gravimetric observations were carried out in the summit area of Mt. Etna in July 2021. Only the north-west half of the planned survey area was accessible to field work due to ongoing intense eruptive activity. The new gravimetric observation points (171 in number) were positioned using precise geodetic positioning based on GNSS technology. Due to rough conditions, unstable ground and wind, the gravity observations were collected with a precision of about 15 microGal using two relative gravimeters (CG5 and CG6). Complete Bouguer anomalies (CBA) were compiled. The computation of accurate topographic correction for CBA compilation poses a challenge because of the ever-changing topography around the summit craters due to intense eruptive activity. Precise topographic correction was computed using the Toposk software. The available high resolution (5 m) DEM released in 2016, and the reference constant topographic density of 2300 kg/m3, which resulted from our analysis as representative for the summit area, were adopted for the numerical evaluation of the topographic correction. These data will serve the 2D and 3D density modelling for determining the subsurface structural model of the summit area and the upper-most part of magma feeders of the summit craters on Etna.
Calibrating tropospheric errors on ground-based GNSS reflectometry: calculation of bending and delay effects
Authors: Feng Peng , Haas Rüdiger , Elgered Gunnar , Strandberg Joakim
Published: March 2022

During the last decade, GNSS interferometric reflectometry (GNSS-IR) has shown great potential for sea level monitoring. In combination with geodetic positioning, GNSS-IR provides a possibility to directly link the sea level measurements to the global terrestrial reference frame. However, many error sources can still be better modeled, and the accuracy of GNSS-IR sea level measurements can be improved. Specifically, we revise the tropospheric error model in ground-based GNSS-IR for sea level applications. Unlike GNSS positioning applications, in GNSS-IR the bending effect is as important as the delay effect. Also, usually very low elevation angle observations are used in GNSS-IR, which makes the atmospheric impact even more important. For the bending effect, we propose a new calculation which takes into account the water vapour content and utilizes the widely used mapping function approach to account for the elevation dependence. For the GNSS-IR atmospheric delay, we revise the geometry of the GNSS signal path for the case of coastal GNSS-IR where the antenna is within < 100 m from the sea surface. The atmospheric delay for the reflected signal is separately evaluated at the surface specular reflection point. The delay from the satellite to the reflection point and the direct signal can both be derived from the zenith delay and mapping function, at their respective local coordinates. The delay from the reflection point to the antenna is obtained assuming an average layer refractivity. We validated our model with ray-tracing radiosonde data. At 2° elevation angle, the new method can correct > 98 % of the atmospheric bending effect, compared to about 88 % with the previously adopted approach. With fewer approximations than the previous approach (directly using the mapping function), the new delay error model is also more accurate but with less absolute improvement of about 3 % compared to the previously existing model.
Surface warming in a coastal current during spring time stratification
Authors: ten Doeschate Anneke , Musgrave Ruth , Hay Alex , Comeau Adam , Richards Clark , Ward Brian
Published: March 2022

The winter hydrography of the Scotian Shelf predominantly consists of warm and salty continental slope water, wedged under
the cool and fresher water of a coastal current. The frontal zone between these water masses is associated with subduction and submesoscale lateral mixing processes. Previous studies have shown that in springtime a transition occurs in which the mixed layer stratifies around a cold intermediate layer. The onset of the spring bloom typically occurs before significant surface restratification has taken 
place, thereby contradicting the critical depth hypothesis.
A monthlong survey of repeat transects with several diving and surface gliders across the Scotian shelf was conducted 
between March and April 2021. During several days of exceptionally calm and sunny conditions vertical profiles of micro-structure temperature, 
and turbulent kinetic energy dissipation rates were obtained. 
A surface warm layer was observed to develop and persist within the upper 10m, as a result of the strong insolation and 
low wind forcing. The use of an autonomous upward microstructure profiler allows us to study the evolution of this layer in detail. 
The profile data are used to estimate vertical heat fluxes at the surface and bottom of the mixed layer, which contribute to the springtime restratification.
We investigate the impact of surface restratification and frontal processes on both the heat budget of the mixed layer, and the export of particulate organic carbon to deeper layers during the spring bloom. The results of this survey help improve our understanding of heat and carbon transfer on the Scotian Shelf.
Nontarget screening exhibits a seasonal cycle of PM2.5 organic aerosol composition in Beijing
Authors: Ma Jialiang , Ungeheuer Florian , Zheng Feixue , Du Wei , Wang Yonghong , Cai Jing , Zhou Ying , Yan Chao , Liu Yongchun , Kulmala Markku , Daellenbach Kaspar , Vogel Alexander
Published: March 2022

The molecular composition of atmospheric particulate matter in the urban environment appears as extremely complex, and it remains a grand challenge to identify its sources and formation pathways. In this study, we applied a novel nontarget analysis to HPLC/(−)ESI-HRMS measurements of yearlong PM2.5 filter samples from Beijing, and represent all detected compounds in comprehensive molecular fingerprints. Additionally, we used a hierarchical clustering analysis (HCA) for complexity reduction of the large dataset. The Van Krevelen-diagram indicate that the major compound clusters exhibit a unique molecular pattern. We found that organic aerosol (OA) in Beijing during summer features a higher degree of oxidation and a higher proportion of organosulfates (OSs) in comparison to OA during wintertime, which exhibits a high contribution from (nitro-)aromatic compounds. OSs appeared with a high intensity in summer-haze conditions, indicating the importance of anthropogenic enhancement of secondary OA in summer Beijing. We estimated the quantitative contribution of the main compound clusters to total OA based on calibrations using surrogate standards. With this approach, we are able to explain a small fraction of the OA monitored by the Time-of-Flight Aerosol Chemical Speciation Monitor (ToF-ACSM). However, we observe a strong correlation between the sum of the quantified clusters and OA measured by the ToF-ACSM, indicating that the identified clusters represent the major variability of OA seasonal cycles. This study highlights the potential of using nontarget screening in combination with HCA for gaining a better understanding of the molecular composition and the origin of OA in the urban environment.
Investigating subsurface conditions favouring the formation of secondary lahars in the glacier forefields of Cotopaxi volcano, Ecuador 
Authors: Frimberger Theresa , Krautblatter Michael
Published: March 2022

Recently deglaciated terrain is highly active and subject to enhanced geomorphological change. The tropical glaciers on Cotopaxi volcano (5897 masl) in Ecuador are rapidly declining and have lost more than 50% of their surface area within the last five decades, and climate models predict a future rise of the Equilibrium Line Altitude of at least 200 m within the next 50 years (Vuille et al., 2018). The retreat of the presumably polythermal glaciers exposes unconsolidated, previously frozen pyroclastic material and moraine deposits on the steep volcano flanks. In recent years, secondary lahars unrelated to obvious trigger mechanisms occurred at Cotopaxi. As these lahars originated in proglacial areas, we aim to explore a potential connection between glacier retreat and lahar formation.

Here, we provide first insights into scarcely investigated subsurface conditions in periglacial areas of tropical glaciers. In order to gain knowledge on the presence of permafrost and ground ice, which can act as an aquiclude and potential detachment plane, we installed temperature loggers at 5-10 cm depth and performed electrical resistivity and seismic refraction surveys in the glacier forefields between 5000 and 5300 masl. The 1.5-year temperature record shows positive mean annual ground temperatures at all six logger sites. However, the temperature-calibrated electrical resistivity tomogram indicates partly frozen ground at depths of 10-20 m, where high electrical resistivities correspond to calibrated rock temperatures of -1.3 °C. We apply a 1-D thermal model to reproduce temperature changes at the surface with depth due to the retreat of cold-based glaciers. It allows to estimate the effect of the pyroclastic cover with high ice contents, which dampens thermal changes by uptake of latent heat during thawing, and can contribute to maintain ice bodies or relict permafrost lenses for years after deglaciation. In this study, we explore the relevance of degrading permafrost and ice lenses for preconditioning periglacial secondary lahars on rapidly deglaciating tropical volcanoes.

Vuille, M., Carey, M., Huggel, C., Buytaert, W., Rabatel, A., Jacobsen, D., Soruco, A., Villacis, M., Yarleque, C. and Timm, O. E. 2018. Rapid decline of snow and ice in the tropical Andes–Impacts, uncertainties and challenges ahead. Earth-Science Reviews, 176, 195-213.
Initial non-uniform soil water redistribution as inherent hydrological process – from field experiments to model insights
Authors: Jackisch Conrad , Allroggen Niklas
Published: March 2022

Proper parameterisation and conceptualisation of the commonplace process of infiltration into the soil is still a topic of debate. Measuring soil water distribution in a spatio-temporally continuous manner can advance our understanding of infiltration in non-uniform flow networks and the soil matrix. At the same time, we find different measurement techniques bound to different concepts and scales, which make a general interpretation and quantification of the data still a challenging task.

We present results from several irrigation experiments at the plot and hillslope scale, in which we combined hydrological, geophysical and remote sensing techniques. On this basis, we will point out how different techniques have advantages and pitfalls for their interpretation. E.g. despite the different scales, we found hydraulic conductivity measured in soil cores in good coherence with plot scale experiments, while in-situ measurements with a constant head permeameter deviated substantially. Another example are multispectral data of the changing surface conditions during irrigation which cannot discern different subsurface infiltration patterns, once the surface becomes sufficiently wet.

Since any parameterisation links back to the conceptual and numerical models, we have developed an alternative concept to simulate soil water infiltration and redistribution based on a Langangian approach using film flow in representative macropores and a 2D random walk for the soil matrix. Simulations highlight the inherently combined effect of antecedent state and connected preferential flow networks on the respective generation of non-uniform infiltration patterns.
Analysis of spatiotemporal rainfall objects in hydrological ensemble forecast predictions 
Authors: Ruiz Gomez Andres Julian , Corzo Perez Gerald , Van Andel Schalk Jan , Santos Granados Germán Ricardo
Published: March 2022

Initial works on forecasting focused their efforts on one-dimensional precipitation time-series analysis. However, rainfall phenomena are sometimes quite heterogeneous and spatially variable in space and time, especially in extreme events. To address this issue, an integrated approach might be needed, where not only the spatio-temporal variability of rainfall is considered, but also the uncertainty that is present in forecasting. The objective of this research is to analyse the relationship between spatio-temporal rainfall objects estimated from numerical weather prediction models and their hydrological response in a river basin. It is assumed that a better understanding of this relation could help to characterize and forecast extreme phenomena. For this study, the Dapoling-Wangjiba catchment is evaluated, where observed precipitation and discharge data from 2006 to 2009 were available. The analysis is based on four main components:  first, the rainfall perturbed members data are obtained through the TIGGE dataset from ECMWF. Second, the object-based methodology ST-CORA is used in order to characterize the possible rainfall events via its spatio-temporal characteristics such as centroid, spatial coverage and duration. Third, a fully distributed and calibrated HAPI model is used for obtaining a simulated discharge in the catchment outlet and finally, an analysis between the statistics of the object’s characteristics and the hydrological response is carried out. The results of this research are expected to be used in future improvements on how forecasting and early warning and nowadays emitted and understood.
New Dam Break Risk Assessment Method in Fuzzy Framework
Authors: Goel Anubhav , Srinivas Venkata Vemavarapu
Published: March 2022

Dams are useful for mitigation of floods, and at the same time there is a risk of dam breach or failure from floods, apart from seismic hazards and factors such as ageing of dam material. In recent decades, there is an alarming increase in dam breach events. This has drawn the attention of hydrologists to have a relook at methodologies being considered for dam risk analysis. Effective risk analysis requires accounting for both failure probability of dam and dam break consequences. There are numerous factors which effect the consequences, and there is considerable amount of uncertainty, vagueness and ambiguity among them due to lack of data and knowledge. To address this, we propose a new dam break risk assessment method in fuzzy framework. It considers fuzzy hierarchical model for risk assessment based on combination of static and variable fuzzy set theory. A hierarchical structure is devised for various factors influencing dam break consequences. Furthermore, weights are assigned to the factors using Fuzzy Analytical Hierarchy Process (FAHP). Thereafter, weighted information of different factors is comprehended to arrive at estimate of a risk index. The effectiveness of proposed method is demonstrated through case study on Hemavathi dam located in upper reaches of Cauvery River basin, India. It is a composite dam with masonary spillway and earthen flanges. The catchment area of river up to the dam site is 2904 sq. Km. Furthermore, height of dam above riverbed level is 44.5 m, and its gross storage capacity is 1047 Mm3. As per Bureau of Indian Standards (BIS) the dam is classified as large dam and therefore qualifies for Probable Maximum Flood (PMF) as design flood. Breach analysis of Hemavathi dam was performed using 1D-2D coupled HEC- RAS model to map the extent of flooding downstream of the dam using PMF (corresponding to 2-day PMP) as inflow and maintaining initial pool level in reservoir at maximum water level (MWL). For comprehensive risk assessment, life loss, economic loss, and social and environmental influence caused by dam break are considered in the model.
Signal contribution of remote areas to cosmic-ray neutron sensors based on distance and sensitivity
Authors: Schrön Martin , Köhli Markus , Zacharias Steffen
Published: March 2022

Cosmic-Ray Neutron Sensing (CRNS) is an established measurement technique for water content in soils and snow. The high integration depth and the large measurement footprint is an important advantage compared to conventional point-scale sensors. However, the radial-symmetrical footprint definition based on the 86% quantile of detected neutrons is often not helpful to explain the influence of certain areas in complex fields. Many natural sites are highly heterogeneous and thus knowledge of the contribution of distant areas to the measurement signal would be very useful, e.g. to support calibration sampling, sensor location design, data interpretation, and uncertainty assessment. Here, CRNS calibration and validation remains a challenge, since the influence of the different fields and structures to the signal is usually not known.

In this presentation, we proposes a generalized analytical procedure to estimate the contribution of patches or fields in the footprint of a cosmic-ray neutron detector to its signal using the radial intensity functions. The proposed method could greatly support calibration sampling, sensor location design, and uncertainty assessment, e.g. in complex or vegetated terrain, without the need of computationally expensive neutron modeling. Furthermore, a new concept for a more practical definition of the sensor footprint is proposed, which represents the maximal distance to a field such that its soil moisture change is still sensible in terms of measurement precision. 
Exploratory analysis of Sub-seasonal to Seasonal precipitation forecasting using Machine Learning Techniques
Authors: Elbasheer Mohamed , Perez Gerald Corzo
Published: March 2022

Sub-seasonal to seasonal (S2S) forecasting ranges from two weeks to two months. This range of time is significant and has a substantial socio-economic impact for many societal applications such as agriculture, food security and risk mitigation because it gives a reasonable margin of time for any management measure (for example, disaster or risk mitigation measures) that need one or two weeks to be implemented. However, the reliability of the S2S forecasting is still underdeveloped, and many studies and even competitions have been promoted to aim at the study of how can Machine learning and other techniques help. So, in this study we evaluate the accuracy and reliability of the ECMWF S2S precipitation forecasts focusing on the extreme events (above and below normal precipitation events) using three verification methods; Receiver operating characteristic curve (ROC), Reliability diagram and Ranked probability skill score (RPSS). For this evaluation, three regions are selected globally. In addition to the accuracy evaluation, we investigated the use of machine learning techniques such as k-nearest neighbors (k-NN), Logistic Regression (LR) and Multilayer Perceptron (MLP) to improve the accuracy and reliability of the ECMWF S2S forecast. To select the appropriate input variables for the machine learning models; An analysis of temporal and spatial continuity of the variables is done using the Pearson correlation coefficient for temporal correlation and the experimental variogram for spatial continuity.
Numerical simulation of the Lagrangian transport of aerosols of various genesis in urban conditions
Authors: Varentsov Alexander , Stepanenko Victor , Mortikov Evgeny
Published: March 2022

This work is devoted to the development of a numerical model of the transport of aerosol particles in the atmospheric boundary layer, as well as its application in idealized cases and studies with a realistic urban surface. Air quality and the distribution of pollutants is one of the major urban problems, and measurement methods can be limited in the complex geometry of the city, which motivates the development of modeling methods.

The model uses the Lagrangian approach to modeling, taking into account the size and mass of each particle, the possibility of aerosol deposition and their collision with various surfaces. The particle motion equation takes into account various parameters of the atmosphere: wind direction and speed, turbulent characteristics. The influence of turbulence on the motion of aerosols can be taken into account in the model using several parametrizations – stochastic Lagrangian models of zero and first order. It is possible to simulate a huge number of particles at the same time. The algorithm is implemented in the C++ programming language.

The model can be used as a separate tool that requires information about the state of the atmosphere as input data - these can be measurement data, results of hydrodynamic modeling, analytically given values. Numerous experiments have been carried out in this mode. The model was verified on exact analytical solutions for light and heavy particles, on the data of field measurements of the concentrations of dust and sand particles. Calculations were carried out in conditions of idealized geometry of buildings (urban canyons) and in conditions of real urban development. For this, input data from RANS and LES models were used.

The developed algorithm can also be used as a module connected to hydrodynamic models. In this mode, it is possible to use the input data on atmospheric parameters with the maximum resolution in time and space. By connecting to the LES model, high-resolution simulations of aerosol transport in realistic urban environments were performed.

The work is supported by Russian Ministry of Science and Higher Education, agreement No. 075-15-2021-574 (megagrant leaded by M.Kulmala in Moscow State University, WP4), No. 075-15-2019-1621, by RSF grant 21-17-00249, by RFBR grants 20-05-00776 and 19-05-50110.
Numerical modeling of fine sediments in a hydro power reservoir
Authors: Maskey Diwash Lal
Published: March 2022

One of the biggest threats to a water reservoir is the storage loss due to sedimentation. Different sediment management strategies are practiced and documented in literature but selecting appropriate ones for a particular reservoir is affected by many parameters that include topography, water volume, sediment volume, costs, and environmental concerns. Physical models are used in verifications of designs of hydraulic structures and modeling bed load transport in rivers. In case of reservoirs, investigations are required for transport of fine sediments in suspension. Here, physical models have limits with scaling and costs of modeling. Numerical models are now increasingly utilized and researched to investigate suspended sediment transport.

In this study, a 3D numerical model is utilized to investigate the transport of fine sediments in a reservoir. The goal is to verify the numerical model with the results from the physical model and then investigate the sedimentation in the prototype scale with fine sediments. This will assist in understanding the temporal and spatial distribution of sediments in reservoir to plan for a suitable sediment handling technique.
Assessment of the impact of climate change on groundwater resources using regional climate model projections: comparison of surrogate modeling techniques
Authors: Tanda Maria Giovanna , Secci Daniele , D'Oria Marco , Todaro Valeria
Published: March 2022

This work compares two different surrogate data-driven models in order to evaluate the effects of climate change on groundwater resources by means of an ensemble of 13 Regional Climate Models (RCM), provided within the Euro-Cordex project, under two different scenarios (RCP 4.5 and RCP 8.5). The impact was evaluated for three future periods: 2006-2035 (short term), 2036-2065 (medium term) and 2066-2095 (long term). Both approaches are based on historical data collected in northern Tuscany, covering the period 2005-2020. Historical precipitation and temperature records, observed in 18 gauging stations, and piezometric levels for 14 wells were used to build the surrogate models. The first methodology is based on a linear regression model and adopted standardized indices: the Standardized Precipitation Evapotranspiration Index (SPEI) and the Standardized Groundwater Index (SGI). First, for each well, the correlations between SPEIs and SGIs were investigated for the period 2005-2020. In case of meaningful correlation, linear regression equations are used to estimate SGIs as function of SPEIs. The linear regression models were then applied to predict future SGIs ​​using SPEIs computed from the data ​​provided by the RCMs projections. The second surrogate technique involves the use of a Long-Short Term Memory (LSTM) neural network. LSTM allows to work directly with climate variables and normalized groundwater levels. The LSTM network was trained using the historical precipitation and temperature time series for the period 2005-2018 as input and the normalized groundwater levels as output. Rain, temperature and piezometric level data from 2019 to 2020 were used to test the network. Subsequently, the rainfall and temperature time series ​​provided by the RCMs have been used by the LSTM to predict the future groundwater levels. The analysis highlights, for both approaches, a negative impact of climate change on the groundwater system. In particular, according to the RCP 4.5 in the medium-term period a larger reduction of groundwater availability is expected, while with the RCP 8.5 the long-term period is the most affected by a groundwater level decline.
Bidimensional Spatiotemporal analysis of local atmospherically fluxes and regional moisture budgets in river basins
Authors: Sanchez Hernandez Karel Aldrin , Corzo Perez Gerald Augusto
Published: March 2022

Many regions in the world are threaten by Climate change, and there is a large global concern on the dependency of water contributions from neighbouring countries. In order to understand more how the water contributions from other region affect a river basin, global spatiotemporal information could be used to obtain budgets balance. This study proposes a methodology to analyse the atmospheric moisture balance around hydrological units (watersheds) using ERA 5 reanalysis data sets, allowing the evaluation of the role of spatiotemporal patterns associated with the transport of regional moisture fluxes and understanding how these components modulate regional water heterogeneity, sources and sinks. This study consists of 3 phases: 1) collection and validation of the required hydrometeorological sets and variables and two-dimensional discretization of the hydrographic domain or unit establishing the boundaries for computational analysis; then, estimation and evaluation of the contribution patterns of transported moisture fluxes based on the Eulerian model developed by Brubaker,1993. Finally, for each region, we proceed to estimate the spatiotemporal variations of the atmospheric water balance by establishing the calculation of the precipitation recycling rate as well as the fractions of horizontal moisture flux contributions from each direction or boundary, as well as their seasonality and interannual variability, magnitudes and concentration rates associated with flux divergence. As a case study, the Pamplonita river basin in Colombia was selected. Here we present these results, that have provided valuable information related to the identification of biases in the estimation of atmospheric water supplies, monitoring strategies and hydrological balance.
Investigation of Nanosecond Pulsed Cold Atmospheric Plasma (NSP-CAP) as a Means to the Highly Energy Efficient Degradation of PFAS in water 
Authors: Aggelopoulos Christos , Papalexopoulou Konstantia , Ronen Avner , Rassias Gerasimos
Published: March 2022

Poly- and perfluoroalkyl substances (PFAS) are a class of organofluorine compounds liberally used over the past 60 years in aqueous film forming foam (AFFF), household products, etc. Perfluorooctanoic acid (PFOA) is widely used, while PFOA water contamination is intense often surpassing the EPA's lifetime health advisory (the limit is 70 ng/L). Due to extensive PFAS contamination in drinking water and their associated health risks, there has been a great focus on developing practical and effective water treatment technologies. Treatment technologies developed so far include adsorptive and destructive methods. Adsorptive methods to date exhibit promising results on the effective removal of some of PFAS but can be expensive and can cause secondary pollution due to the generation of PFAS contaminated residues. On the other hand, due to the recalcitrant nature of PFAS and the C–F bond, destructive methods face important challenges.[1] A promising destructive treatment technology which is well-established for its efficiency to remove a wide range of persistent contaminants in water is Cold Atmospheric Plasma (CAP) exhibiting advantages such as high energy efficiency, effectiveness, rapidness, and green character.[2] In this study, a novel highly energy efficient CAP method is implemented for the degradation of PFOA in water. A nanosecond pulsed (NSP) generator with a rising time of 4 ns and an in-liquid configuration of the CAP reactor for the direct generation of plasma species in the form of bubbles inside water, were used in order to maximize the energy efficiency of the process. The impact of the most critical parameters including treatment time, pulse voltage/frequency, plasma gas, PFOA initial concentration, etc. have been examined in detail for the method optimization.
Status of the Ganymede Laser Altimeter (GALA) for ESA’s JUICE Mission
Authors: Hussmann Hauke , Lingenauber Kay , Kallenbach Reinald , Lüdicke Fabian , Enya Keigo , Thomas Nicolas , Luisa M. Lara , Touhara Kazuyuki , Masanori Kobayashi , Jun Kimura
Published: March 2022

The Ganymede laser-altimeter (GALA) is one of 10 instruments on ESA’s Jupiter Icy Moons Explorer (JUICE) mission. The scientific goals cover a wide range  from geology, geophysics to geodesy of the icy moons Ganymede, Europa and Callisto. JUICE will explore Jupiter, its magnetosphere and satellites first in orbit around Jupiter before going finally into polar orbit around Ganymede.  GALA is developed under responsibility of the DLR Institute of Planetary Research in collaboration with industry and institutes from Germany, Japan, Switzerland and Spain. GALA has two main objectives: (1) providing Ganymede’s topography from global to local scales (2) determination of Ganymede's tidal variations of surface elevations. GALA is a single-beam laseraltimeter: a laser pulse (1064 nm) is emitted by using a Nd:YAG laser firing at 30 Hz (nominal). After about 3 msec (500 km altitude) the reflection of the pulse from the surface of Ganymede is received by a telescope and transferred to the detector (Avalanche Photo Diode). The signal is digitized and transferred to the range finder module, which determines (a) time of flight (b) pulse shape, and (c) energy of the received pulse. Including information on the spacecraft position and attitude the height of the terrain above a reference surface is determined for each shot from time-of-flight measurements. The GALA flight model was delivered to ESA in August 2021. After several tests on instrument level the integration on the JUICE spacecraft started in September 2021 and first tests were performed successfully in October 2021. With the launch scheduled for 2023, GALA will go through several tests, among them an end-to-end test including laser-receiver measurements. Here we present the instrument's current status with respect hardware integration and regarding the verification of its performance.
Evaluation of potential nitrogen mineralization and relations to static and dynamic soil properties from arable agricultural soils following ten years in Flanders, Belgium
Authors: Banaty Oka Ardiana
Published: March 2022

Soil N mineralization is a crucial parameter for efficient N management in intensive agriculture and is determined by a combination of static or inherent (mineralogy, texture) and dynamic soil properties. We measured N mineralization potential from native soil organic matter (SOM) of 21 agricultural fields under intensive management in 2018-2019 and compared these to N mineralization potential measured on the exact locations in these fields in 2009. We hypothesized that changes in N mineralization over this decadal period could be explained by differences in land management and would be reflected in soil biochemical and physical properties. The results showed that potential N mineralization assessed in 2018-2019 was higher than measured in 2009. However, the changes of N mineralization potential was not significantly correlated with pH-KCl, N total, TOC, C: N ratio and microbial activities (Cmic). Likewise, it was not significantly associated with texture (% sand, % silt and % clay). Therefore, in this study, the potential of N mineralization could be more affected by changes in land management practices (i.e. fertilization, crop rotations and soil tillage) than soil properties following ten years.
Skillful Prediction of Barents Sea Phytoplankton Concentration
Authors: Fransner Filippa , Årthun Marius , Bethke Ingo , Counillon François , Samuelsen Annette , Tjiputra Jerry , Olsen Are , Keenlyside Noel
Published: March 2022

The predictability of phytoplankton abundance in the Barents Sea is explored in the CMIP6 decadal prediction runs with the Norwegian Climate Prediction Model (NorCPM1), together with satellite data and in situ measurements. The model successfully predicts a maximum in the observed phytoplankton abundance in 2007 up to five years in advance, which is associated with a strong predictive skill of 2007 minimum extent of the summer sea ice concentration. The underlying mechanism is an event of anomalously high heat transport into the Barents Sea that is seen both in the model and in situ observations. These results are an important step towards marine ecosystem predictions.
Seasonal and Diurnal variations of Kelvin–Helmholtz waves at Earth’s Magnetopause
Authors: Kavosi Shiva , Raeder Joachim , Farrugia Charles
Published: March 2022

We survey one solar cycle of in situ data from the NASA THEMIS (Time History of Events and Macro scale Interactions during Substorms) and MMS (Magnetospheric Multiscale) missions to identify Kelvin–Helmholtz Instability (KHI) along Earth’s magnetopause flank. We found that KHI occurrence rates exhibit semiannual and diurnal variations; the rate maximizes at the equinoxes and minimizes at the solstices. The rate varies for different IMF By polarities; it is maximum around fall equinox for negative IMF By, while is maximum around spring equinox for positive IMF By. The rate is directly related to the dipole tilt angle. Therefore, the equinoctial hypothesis explains most part of the seasonal and diurnal variation of KHI, while the angle of the Earth's dipole in the plane perpendicular to the Earth‐Sun line explains the difference between KHI occurrence rates with positive/negative IMF By. These results reveal the key role of Sun-Earth geometry on modulating the KHI and thus the importance of Earth’s dipole tilt and Sun solar declination angle as a function of time for plasma transport across the magnetopause.