bluuebunny/crossref_metadata_2025 huggingface dataset:
EPOS-GNSS – Current status of service implementation for European GNSS data and products
Authors: Fernandes Rui , Bruyninx Carine , Crocker Paul , Socquet Anne , Vergnolle Mathilde ,   EPOS-GNSS Members
Published: March 2022

EPOS-GNSS is the Thematic Core Service being implemented in the framework of the European Plate Observing System (EPOS) focused on management and dissemination of GNSS (Global Navigation Satellite Systems) Data and Products. The European Research Infrastructure Consortium (ERIC) has provided to EPOS a legal personality and capacity that is recognised in all EU Member States that permits to provide open access to a large pool of Solid Earth science integrated data, data products and facilities for researchers.

The GNSS community in Europe is benefiting from EPOS ERIC to create mechanisms and procedures to harmonize, in collaboration with other pan-European infrastructures (particularly EUREF), the access to GNSS data, metadata and derived products (time-series, velocities, and strain rate maps) that primarily are the interest of the Solid Earth community but ultimately benefit many other stakeholders, particularly data providers and other scientific and technical applications.

In this presentation we focus on the three main components that since last year have entered in the pre-operational phase: (a) Governance – with the aim that the entire community, from data providers to end-users, will be represented and their efforts recognized; (b) GLASS – the in-house dedicated software package developed for the dissemination of GNSS data and products with rigorous quality control procedures; (c) Products – internally consistent GNSS solutions of dedicated products (time-series, velocities and strain-rates) created from the available data set using state-of-art methodologies to be used to improve the understanding of the different Solid Earth mechanisms taken place in the European region.
Talking together about climate risks and dynamics so it enables resilience and trust
Authors: Bruun John
Published: March 2022

The topic of risks in our climate and geosciences setting is highly emotive. When a sudden and extreme event occurs, the emotional consequences of an absence of any planning or mitigation can be severe to the communities and people involved. There are multiple parts of society that are impacted across these events. Where there is an absence of awareness around the issues of equality, diversity and inclusivity (EDI) then, disappointingly, it is typically the disadvantaged groups in that society that are the most impacted. With the raised awareness around the consequences of anthropogenic heating of the planet, we are now faced with increasing occurrence of sudden extreme events and where the underlying dynamic baseline is changing. The hazard probability of extreme levels for an environmental process can be estimated using methods based on statistical extreme value theory (see for example Bruun and Tawn, 1998, Appl. Statist., 47, 405-423). Also the dynamics of the system can be evaluated using non-linear methods (e.g. see Bruun et al, 2017, JGRO, 122, 6746– 6772 and refs in this). These methods are generic and are applied in seismic, flooding and weather based settings. I’ll show with graphics examples of precipitation hazards for the tropics to explain sudden and long term dynamics. These methods are being deployed more and more in terms of framing climatic hazards, however there are analytical challenges in building in the slow-variation to the methods so that real long term hazards are skilfully assessed. Also the mathematical formulation these methods are typically utilized by analysts, scientists, engineers and mathematicians. It is found that the mathematical formulations present a communication barrier to hazard and resilience practitioners, especially as the contemporary EDI framing of this skill set is often not very diverse. In this talk, to help re-frame this, an open discussion of this topic is invited – please do join – to enable a wider community access.  To help this I will share and  some contemporary thinking developed i) at the University of Exeter: where I am a Mathematics Lecturer, Diversity Champion for our College of Engineering, Mathematics and Physical Sciences and also ii) from the Institute of Physics (IOP) and its Limit Less campaign. By re-framing – together - how we communicate about these hazards, using an EDI lens, it can help us to better connect through our communication, and so to build more trust in the knowledge. This type of discussion can help hazard practitioners, stakeholders and importantly to help build trust and resilience for all groups how are impacted by such extreme events.
Observed changes in sea breezes over the Western Mediterranean basin, 1961-2020 
Authors: Bedoya-Valestt Shalenys , Azorin-Molina Cesar , Gimeno Luis , Cafaro Carlo , Utrabo-Carazo Eduardo , Andres-Martin Miguel , Guijarro Jose A. , Aguilar Enric , Brunet Manola
Published: March 2022

Climate change may affect sea breezes in their magnitude and occurrence, having direct implications for the hydrologic cycle and desertification (i.e., development of sea breeze thunderstorms), air pollution dispersal, wind energy production, to name but a few. To date, trends and multidecadal variability of sea breezes have been barely quantified because of the scarcity of long-term series, the low spatial-temporal resolution and the unreliability of observations over land-sea surfaces. Recent studies showed an increase in the occurrence of sea breeze days for the Eastern Spain, as well as opposite trends between the mean speed and gusts. The causes behind these opposite trends remain unknown because of the complexity of thermally driven coastal wind systems. The aim of this study is to advance in the knowledge of the observed changes in sea breezes over the Western Mediterranean area for 1961-2020, and their likely causes. To do so, we will first apply a robust automated algorithm based on alternative criteria to detect potential sea breeze events. Then, we will use homogenized wind speed and gusts data from sub-daily observations across the Mediterranean region to quantify the magnitude and significance of changes in sea breezes for 1961-2020. Finally, we will estimate the relationship with large-scale circulation (e.g., modes of variability, weather types and mean layer vector wind) and physical-local factors (e.g., land use changes and land-sea air temperature gradient) from ERA5 reanalysis to better understand the likely causes behind the observed changes in sea breezes.
Reliability metrics for permanent water network partitioning
Authors: Santonastaso Giovanni Francesco , Di Nardo Armando , Greco Roberto
Published: March 2022

The reliability of water distribution networks (WDN) can be defined as the ability of the system to meet water demands under both normal and abnormal conditions (Bao and Mays, 1990). The measure of reliability is influenced by many factors: possible failure of one or more components, unusual high demand, connectivity of the network, poor water quality, etc. Although reliability of WDN was originally defined by Goulter (1987) and Walters (1988), measuring reliability is an open challenge for researchers. Consequently, there is no established measure of WDN reliability.

In recent years, many studies have attempted to mathematically define the reliability of water distribution networks and several synthetic indices are provided as proxy of reliability measures. The objective of this paper is to investigate the suitability of two of these metrics: one based on surplus of power head and other   on Shannon’s informational entropy for the assessment of reliability of partitioned water distribution networks (WDNs). The creation of permanent DMAs involves permanently an alteration of the WDN by closing multiple lines at the same time, and, therefore, it is a more severe test than those commonly used in the scientific literature where a little or no disruption occurs to the operation of the WDN (e.g., segment isolation or demand amplification). In addition, the two metrics were compared with other known indicators of hydraulic performance to determine which of them is better suited to evaluate the reliability of water network partitioning. For this purpose, a medium-sized water distribution network in South of Italy was used as case study and the hydraulic simulations were performed with a pressure-driven approach using EPANET2.2 software.

 

References

Bao, Y., Mays, L.W. (1990). "Model for water distribution system reliability",  J. Hydrual. Eng., 116, 1119-1137

Greco, R., Di Nardo, A., Santonastaso, G.F (2012). "Resilience and entropy as indices of robustness of water distribution networks", J. Hydroinformatics, 14 (3), 761–771.

Gouher, I.C. (1987). "Current and future use of system analysis in water distribution network design", Civ. Engrg. Sys., 4(4), 175-184.

Walters, G. (1988). "Optimal design of pipe networks: a review." Proc.,1st Int. Conf. on Compo and Water Resour., Vol. 2, Computational Mechanics Publications, Southampton, U.K., 21-31.
Uptake of micropollutants from treated wastewater, sewage sludge and composted sewage sludge by plants
Authors: Kodešová Radka , Švecová Helena , Klement Aleš , Fér Miroslav , Nikodem Antonín , Kočárek Martin , Chroňáková Alica , Grabic Roman
Published: March 2022

Various micropollutants (including pharmaceuticals, UV filters, cosmetics, cleansers, etc.), are increasingly being detected in the environment because of their partial or incomplete removal from wastewater in wastewater treatment plants (WWTPs). These compounds can be taken up by plants if treated wastewater is used for irrigation or if biosolids are used for soil amendment. Previous studies focused on this subject were usually performed under greenhouse conditions. Therefore, the aim of this study was to evaluate a behavior of studied compounds under natural climatic conditions. Experiment was carried out directly in the wastewater treatment plant, where nine raised beds were installed, which contained soils taken from topsoil of two soil types Arenosol (two beds) and Cambisol (seven beds). Either maize or a mixture of different vegetables (lettuce, carrot and onion) was grown in these beds. Of the seven beds with the Cambisol, one of the beds containing either maize or vegetables was irrigated with tap water and other pair of beds (maize or vegetables) was irrigated with treated wastewater (i.e., WWTP effluent). In another pair of beds (maize or vegetables), composted sludge from WWTP Three beds containing both types of biosolids were irrigated with tap water. Only vegetables were grown in the beds with the Arenosol, which were irrigated with either tap water or treated wastewater. Climatic data, irrigation doses, drainage water volumes, soil water contents and plant growth were monitored during the experiment. Selected compounds concentrations were measured in WWTP effluent, both biosolids, drainage water, soils, and plant tissues. Fifty five of 77 analyzed compounds were quantified in WWTP effluent. Main compounds were pharmaceuticals (e.g., telmisartan, gabapentin, diclofenac, carbamazepine, and its metabolites), UV filters (e.g., phenylbenzimidazole sulfonic acid) and compounds used in anticorrosive paints (e.g., 1H-benzotriazole). In the case of both biosolids, the dominant compounds were telmisartan, sertraline, trazodone, citalopram, diclofenac (i.e., pharmaceuticals) and 1H-benzotriazole. Uptake of different compounds by plants depended on a plant and properties of organic molecules, which affected their sorption in soils and mainly their ability to be taken up and translocated in plants. For instance, pharmaceuticals carbamazepine, gabapentin tramadol and venlafaxine were mainly found in lettuce leaves.

 

Acknowledgement: Study was supported by the Ministry of Agriculture of the Czech Republic, project "The fate of selected micropollutants, which occur in treated water and sludge from wastewater treatment plants, in soil" (No. QK21020080) and partly also by the European Structural and Investment Funds, projects NutRisk (No. CZ.02.1.01/0.0/0.0/16_019/0000845).  
Simulating the effects of erosion on organic carbon dynamics in agricultural soils
Authors: Lin Honghong , Duan Xingwu , Li Yawen , Zhang Lanlan , Rong Li , Li Ruimin
Published: March 2022

Soil erosion in croplands has a strong impact on global carbon (C) cycle. Assessment of erosional effects on soil organic carbon (SOC) dynamics in agricultural soils suffers from the difficulty of distinguishing the erosional effects and complex interaction processes between erosion and C cycling. To simulate the effects of soil erosion, a plots experiment including six erosion levels (0, 5, 10, 20, 30, and 40 cm eroded) was conducted for seven years (2012-2018). The erosion levels were simulated using artificial soil profiles created by mixing soils from different layers in the original soil profile (never eroded) in a certain proportion. Subsequently, based on the field observations during 2012-2018, the SOC dynamics of each experimental plot were simulated by using a process-oriented C cycle model (denitrification-decomposition (DNDC)) to quantify the effects of erosion on SOC dynamics. The measurements at the beginning of the plots experiment showed that simulated erosion resulted in the depletion of SOC with an average reduction rate of 9.7% per 10 cm of soil loss; SOC in eroded soils recovered after seven years of cropping, the declining slope of the SOC measured in 2018 was 3.0% per 10 cm of soil loss, suggesting that dynamic replacement had occurred. Model simulation results indicated that soil erosion could reduce the C inputs from crop residue by lowering soil productivity; soil heterotrophic respiration in eroded soils was restricted due to the lower initial SOC content. As a result, the simulated overall SOC stock in eroded soils was restored after erosion stopped because of the lower C output. These results indicated that SOC loss at eroding sites was caused mainly by lateral transport rather than enhanced decomposition. The fate of the displaced SOC within catchments is key to assess the net impacts of soil erosion on SOC dynamics at a large scale.
Changes in Aerosols in an Urban Cold Climate During and Before the COVID-19 Outbreak
Authors: Ashraf Samaneh , Pausata Francesco S.R. , Leroyer Sylvie , Munoz-Alpizar Rodrigo
Published: March 2022

Atmospheric aerosols are of significant importance in climate change and health research and are essential to consider in air quality and climate modeling. Quebec is the second-largest province in Canada by population and much of the population lives in urban areas. Limitation of public activities, public transportation as well as some suspended operations of educational institutions and many commercial establishments in Quebec while severe lockdown policy was implemented, had strong repercussions on the pollutant concentration level. By analyzing a combination of air pollutants observational data (e.g. CO, SO2, PM10, O3, and NO2), this study attempts to investigate the impact of lockdown due to the COVID-19 pandemic on the pollution level of the local urban environment. Since meteorology can play an important role in air quality, the variation in diverse meteorological factors (e.g. temperature, humidity, wind, pressure, and sunlight) is evaluated as well. By separating long-term trends, seasonal signals, and meteorological contributions concerning climatology, this study estimates the relative contributions of human activities to changes in particulate concentrations. We herein discuss the implications of these results on air quality and climate modeling.
Laboratory experimental study on wave-turbulence interactions
Authors: Ma Hongyu , Dai Dejun , Jiang Shumin , Huang Chuanjiang , Qiao Fangli
Published: March 2022

Surface gravity waves play an important role in the mixing process of upper ocean. How wave energy is transferred to ocean turbulence through the wave-turbulence interactions remains an open question. Here, laboratory experiments were designed and performed in a wave tank to investigate wave-turbulence interactions in detail. The turbulence intensities before and after the wave-turbulence interactions were compared quantitatively based on their power spectra, and the experimental results indicate that the background turbulence increased approximately by 23.3% through wave-turbulence interaction between 7 and 20 Hz of the power spectrum. Using the Holo-Hilbert spectral analysis method, the results clearly show that the turbulence was modulated by surface waves and then enhanced through the wave-turbulence interaction process. When the wave height was 3 cm and 5 cm, the modulation mainly occurred in the wave trough phase which is consistent with previous literatures. However, the modulation occurred in both the wave trough and crest phases when the surface wave was strong with a wave height of 7 cm. In addition, the intensity of the wave-turbulence interaction increases with the wave height and is proportional to .
Assimilation of ERT data to improve Feddes parameters in a hydrological model during a root water uptake experiment
Authors: Mary Benjamin , Botto Anna , Iván Veronika , Peruzzo Luca , Chou Chunwei , Wu Yuxin , Cassiani Giorgio , Camporese Matteo
Published: March 2022

Mitigating plant water stress while reducing irrigation is one of the biggest challenges that sustainable agricultural practices aim to tackle. The rhizosphere is the main unknown component controlling the water distribution in the soil, but non-destructive observations of root physiology are often lacking due to methodological limitations.  

Numerous studies relate the use of electrical resistivity tomography (ERT) or stem-based methods to measure soil water content changes associated with root water uptake (RWU) in the rhizosphere area. Nevertheless, geoelectrical data are correlated with many rhizosphere parameters and their interpretation needs to be supported by physics-based models of root hydrology.

Here, we use a Data Assimilation (DA) framework to combine geoelectrical data with a hydrological model (Mary et al. 2021). DA offers the possibility to estimate model parameters governing RWU, such as in the well-known Feddes approach while introducing data observations to update them. 

In a synthetic experiment mimicking a top-down infiltration in a rhizotron containing a wine plant (Vitis Vinifera), we simulated different scenarios of ERT data assimilation with the CATHY surface-subsurface hydrological model. The rooting depth associated with the Feddes parameters are perturbed to generate the ensemble states. At each observation time, model states and root depth parameters are updated using the Ensemble Kalman Filter (ENKF). 

Expected results aim to demonstrate (i) what is the best ENKF scheme to integrate ERT measurements with the hydrological model and (ii) how much the uncertainties on the Feddes parameters can be reduced with the assimilation of ERT data. In a future work, the best approach identified will be applied to real soil and plant observation datasets.

Mary, B., Peruzzo, L., Iván, V., Facca, E., Manoli, G., Putti, M., et al. (2021). Combining Models of Root-Zone Hydrology and Geoelectrical Measurements: Recent Advances and Future Prospects. Front. Water 3, 767910. doi:10.3389/frwa.2021.767910.
Recirculation and trapping of tidal plume fronts and internal wave generation in the Rhine ROFI
Authors: Pietrzak Julie D. , Rijnsburger Sabine , Flores Raul , Horner-Devine Alexander , Souza Alejandro , Lamb Kevin , Jones Nicole
Published: March 2022

River plumes dominate transport and mixing in our coastal oceans. We present data and introduce a conceptual picture showing how a multi-frontal, mid-field river plume can form, and how the newly released tidal plume fronts can generate multiple internal solitary waves. We focus on the analysis of data and 3D modelling of the Rhine ROFI, and discuss how a recirculation zone forms in the near to mid-field plume.  Our data show the presence of tidal plume fronts, as well as relic tidal plume fronts. It also shows two internal solitary wave packets ahead of a new tidal plume front. Tidal advection and a strong recirculation is found to trap tidal plume fronts within 20 km from the river mouth. This trapping maintains the multi-frontal system. We find that when tidal straining is large, the tidal plume fronts re-strengthen due to increased convergence. The recirculation zone is populated by multiple tidal plume fronts that return to the near field plume, and subsequently interact with the newly forming tidal plume front that discharges freshwater on the ebb tide. Understanding near-to mid-field river plume systems is important for our understanding of along and cross-shore exchange and mixing. Ocean models typically do not resolve non-hydrostatic internal solitary waves, we discuss how this may limit our understanding of mixing in near to mid-field river plumes.
Evaluation of Delft3d Microplastic Model of the Mid-Atlantic New Jersey Coast Using Summer and Winter Field Measurements
Authors: McCormack Tyler , Sherman Anya , Watkins Lisa , Obando Frank , Hopkins Julia
Published: March 2022

As microplastics are being discovered on every corner of the earth, it is imperative to understand how they get there. Modeling capabilities of both the hydrodynamic processes and particle behavior are improving, but it remains expensive to collect and identify microplastics in coastal settings. This highlights the need for and potential of accurate marine debris models. This project compares microplastic deposition field measurements and model predictions on the New Jersey, USA coastline. The objective is to better understand the primary hydrodynamic forcing mechanisms of marine debris. Here, we test the hypothesis that the ability of the model to capture the longshore distribution of microplastic deposition is sensitive to hydrodynamic conditions, particle density, source location(s), and beaching and resuspension rates.

We created a regional hydrodynamic model in Delft3D of the New Jersey coastline from back bay river mouths to 50km offshore, using tidal, wind, wave, and river discharge conditions from 2016. We ran the model from January 1st, 2016 until December 31st 2016 to capture the seasonality of the flow and wind conditions. We used the Delft3D particle tracking module to insert particles with properties (e.g. particle density, horizontal diffusivity, and beaching probability) defined to best represent the behavior of microplastic particles and monitor their transport and fate. To assess the ability of a regional hydrodynamic model paired with a particle tracking module, 28 beaches were selected from the New Jersey coastline and sampled for microplastics (1-5mm) using methods similar to the US Environmental Protection Agency’s Microplastic Beach Protocol that detail consistent and characteristic microplastic measurement techniques of sandy beaches. The same sites were measured once in the winter of 2020/2021 and again in summer 2021 in an effort to capture the different seasonal flow regimes of the Mid-Atlantic coast. 

Here, we show the comparison between the predicted microplastic deposition on the New Jersey coastline to the measured microplastic distribution for both the summer and winter. We assess the ability of the model to predict transport and deposition of various types and densities of microplastic debris. We illustrate the power that particle tracking models have to capture the transport and fate of microplastic debris and highlight the limitations of such models that need to be addressed. Further, we discuss the importance of predictive microplastic models for targeting specific geographical regions for cleanup and mitigation efforts. 
Development of Throughfall Simulation Models and Prediction Uncertainty Estimation by Different Forest Stand Characteristics
Authors: Yang Hyunje , Lim Honggeun , Choi Hyung Tae , Lee Jiyoung
Published: March 2022

Continuously increasing demand for freshwater makes many scientists study water yield prediction. In South Korea, of which two-third is covered by forests, understanding the water cycle especially in forests is even more important. Throughfall is penetrated rainfall through the tree canopy and it is the basic source for groundwater recharge which is directly related to the water yield on the catchment scale. Therefore, understanding the throughfall characteristics is essential for sustainable water management. This study is conducted to develop simple throughfall simulation models and estimate prediction uncertainty from developed models by different forest stand characteristics. National Institute of Forest Service (NIFoS) has collected throughfall data for 2 years from 7 different forest stand sites. Rutter model was used for the structure of the simple throughfall simulation model and it had several parameters for simulating. And over a million Monte Carlo experiments and generalized likelihood uncertainty estimation (GLUE) methodology were used for selecting parameters sets of behavioural models from comparing simulated throughfall and observed throughfall. From the range of behaviours in a period, we successfully estimated the prediction uncertainty. We also compared the features of behavioural parameter sets by different forest stand characteristics. We expect developed models can be applied for several forest stands in South Korea with various physical-based hydrological models.
Precipitation retrievals from cross-track sensors: initial results and validation of the TROPICS precipitation product.
Authors: Kidd Chris , Matsui Toshi
Published: March 2022

The estimation of precipitation from satellite sensors is crucial for measuring precipitation at the global scale. Due to the variability of precipitation, both temporally and spatially, it is necessary to exploit observations from both passive microwave imaging and sounding instruments, as well as visible/infrared observations. While visible/infrared techniques provide frequent sampling with reasonable resolution, the relationship between the cloud top properties and surface precipitation are often poor. Passive microwave observations are sensitive to the presence of the precipitation particles themselves and therefore the observations are more directly related to the precipitation at the surface. Exploiting both passive microwave imagers and sounders is necessary to ensure reasonable temporal sampling. The compact nature of passive microwave sounders has allowed these sensors to be developed for cubesats, such as the Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission. This mission comprises of a total of 7 cubesats, an initial pathfinder launched in June 2021, followed by 6 more to be launched mid-2022. The pathfinder is currently in a polar orbit while the following 6 satellites will be in a low-inclination orbit, providing frequent observations across the Tropics. Each cubesat carries a passive microwave sounder gathering observations from 91.665 GHz to 204.8 GHz in a cross-track scanning mode with spatial resolutions similar to the current Microwave Humidity Sounder sensors. The Precipitation Retrieval and Profiling Scheme (PRPS), initially developed for the larger sounding instruments, has been adapted for use with the TROPICS observations. The PRPS uses an a priori database against which observed radiances are compared and the associated precipitation intensities retrieved. Initial results from the pathfinder will be presented, together with validation against surface reference data sets. These results are promising and show that the retrievals are comparable with other passive microwave sounding instruments.
Ocean break-up and related mountain rise controlled by a continentalcrustal root
Authors: Makushkina Anna , Tauzin Benoit , Miller Meghan S. , Tkalčić Hrvoje , Thybo Hans
Published: March 2022

Large-scale topography is thought to be mainly controlled by active tectonic processes. Fennoscandia is located far from any active tectonic setting and yet includes a mountain range along its passive North Atlantic margin. Models proposed to explain the origin of these enigmatic mountains are based on glacial isostatic adjustments, delamination, long-term isostatic equilibration, and dynamic support from the mantle, yet no consensus has been reached.

Here we demonstrate that Precambrian lithospheric structure of Fennoscandia controlled both Cenozoic oceanic breakup and recent mountain rise in the North Atlantic region. Fennoscandia formed by amalgamation of Proterozoic and Archean continental blocks; using both S- and P-receiver functions, we discovered that the Fennoscandian lithosphere still retains the original structural heterogeneity and its western margin is composed of three distinct blocks. The southern and northern blocks have relatively thin crust (~40-45 km), while the central block has thick crust (~60 km) that most likely was formed by crustal stacking during the Proterozoic amalgamation. The boundaries of the blocks continue into the oceanic crust as two major structural zones of the North-East Atlantic, suggesting that the Fennoscandian amalgamation structures determined the geometry of the ocean opening. We found no evidence for mountain root support or delamination in the areas of high topography that could be related to the mountain formation. Instead, our results suggest that the geometry of the observed features creates conditions favorable for edge-driven convection at the adjacent narrow margins that provides dynamic support for the mountains in Scandinavia.
Distinct Upward Propagation of the Westerly QBO in Winter 2015/16 Compared to 2019/20 and its Relationship with Brewer-Dobson Circulation
Authors: Kang Min-Jee , Son Seok-Woo , Chun Hye-Yeong
Published: March 2022

The quasi-biennial oscillation (QBO), describing alternate easterly and westerly winds in the tropical stratosphere, originally shows downward phase propagation with time. However, in February 2016 and January 2020, downward-propagating westerly winds were split into two with one propagating upward and the other propagating downward, so-called a QBO disruption. Previous studies have mainly focused on the cause of the localized negative momentum forcing initiating the QBO disruption. However, the upward displacement of the westerly QBO followed by the negative momentum forcing, clearly seen in 2015/16 but not in 2019/20, has not been investigated in detail. Here, we show that the distinct upward propagation of the westerly winds in 2015/16 can be explained by the stronger Brewer-Dobson circulation (BDC) using MERRA-2 global reanalysis data. We found that strong Rossby waves with wavenumbers 1 and 2 propagating from the troposphere mainly induce the strong BDC in 2015/16. Potential contributions of El Niño and Barents–Kara sea ice reduction to wavenumber 1–2 Rossby waves are also discussed.
On artificial daily and weekly periodicities of recorded earthquake frequencies
Authors: González Álvaro
Published: March 2022

Levels of artificial seismic noise are typically lower at night, when road and train traffic, industries and other human activities are decreased. Such a variable noise hampers detection of small earthquakes preferentially during daytime, so typically they are more frequently recorded at night. Small earthquakes are recorded in higher numbers during the weekends too, also due to the lower artificial noise. Daily variations of earthquake frequencies might also have natural causes, but higher numbers of earthquakes recorded during weekends are unequivocally artificial.

These variations of detection capabilities are usually not well taken into account when looking for natural periodicities of earthquake frequencies, for example when searching for correlations of earthquake occurrence with diurnal or semidiurnal tides.

Featuring examples from different, regional, earthquake catalogues, this presentation shows that using a magnitude of completeness (Mc) calculated from the whole catalogue can be misleading. The reason is that such a value is actually an average between lower Mc values reached during the night (and weekends) and higher ones reached during the day (and working days).

The solution proposed here is to use a high enough Mc value such as the artificial (daily and weekly) periodicities of earthquake frequencies are removed, considering not only the best estimate of Mc but also its uncertainty range.
Measurement and modeling of slope-wash and rill erosion on hillslopes using a novel combination of instrumented plots and remote sensing
Authors: Pelletier Jon , Abramson Nathan , Chataut Satya , Ananthanarayan Sriram , Ludwick David
Published: March 2022

We have measured unit sediment fluxes and their relationship to unit water discharges over 7 orders of magnitude on hillslopes of up to 350 m in length in Arizona. Unit sediment and water fluxes were measured using a novel combination of instrumented monitoring plots and repeat photogrammetric surveys analyzed volumetrically. The monitoring plots, which are ideal for measuring sediment fluxes in relatively planar portions of the landscape dominated by slope-wash erosion, funnel water and sediment into a detention basin where bedload sediment fluxes are measured and then into a flume where water discharges and suspended sediment fluxes are measured at 1-minute intervals using a pressure transducer and calibrated turbidity sensor. Repeat photogrammetric surveys complement the monitoring plots by measuring sediment fluxes in rills that tend to form in areas of convergent flow during intense rain events. The volumetric change in each pixel is digitally routed to determine the volumetric sediment flux in each pixel associated with rilling during a rain event. Unit water discharges for every pixel cannot be measured directly but are estimated using a rainfall-runoff model calibrated to the monitoring plot data. The relationship between unit sediment fluxes and unit water dischargees exhibits two piecewise power-function relationships with different exponents characterizing the slope-wash and rill-dominated regimes. We developed a novel landscape evolution model, inspired by the SIBERIA model but improved in specific ways optimized for hillslopes, that uses the measured piecewise power-function relationship between unit sediment fluxes and unit water discharges to predict hillslope evolution from time scales of individual events to decades. The predictions of the model are validated using ten years of observation of rill development at the study site. We provide equations for estimating the parameters of the piecewise power-function relationship for other hillslopes with different cover characteristics. This measurement and modeling framework must be tested at more study sites but is potentially useful for predicting the erosion of any hillslope, including alternative designs for landscape rehabilitations following mining or other anthropogenic disturbances.   
Geochemical models help to understand the influence of climate change and intensive groundwater extraction in the chemical composition of a tropical, maar lake in Central Mexico
Authors: Olea-Olea Selene , Alcocer Javier , Silva-Aguilera Raúl , Escolero Oscar , Oseguera Luis A.
Published: March 2022

The tropical maar Lake Alchichica lays in the high altitude (> 2,000 m a.s.l). The orographic shadow of the Sierra Madre Oriental generates a semiarid climate with a negative water budget (1 to 3) so the lake's water balance depends on groundwater. Nonetheless, the decreasing trend of the water level from 1959 on suggests a combined effect of climate change and increasing groundwater extraction (agriculture, urban). Applying geochemical models to explore the interaction between groundwater and surface water allow to identify the geochemical source of the reported increase in sulfate, magnesium, and chloride concentration in the lake water and its relation to climate change and intensive extraction of groundwater. Thirty-five groundwater samples were obtained from wells surrounding Lake Alchichica. Samples were analyzed for major ionic composition and trace elements. We generated a conceptual model of groundwater-surface water interaction and conducted inverse and evaporation geochemical models using the PHREEQC code. Geochemical models explore the water-rock processes between groundwater and geologic materials, understanding the chemical evolution of the groundwater flow system, and understanding the influence of groundwater chemical characteristics in the chemical composition of the lake. This investigation unravels how climate change and intensive groundwater extraction define the way in which: 1) groundwater influences the chemistry of the lake, and 2) to understand the chemical changes that have been reported in the lake.
Accuracy requirements of the gravity measurements for sub-centimetre geoid
Authors: Foroughi Ismael , Pagiatakis Spiros , Goli Mehdi , Ferguson Stephen
Published: March 2022

In this contribution, we estimate the uncertainty (error) of the input gravity measurements needed for the determination of the geoid with an internal sub-centimetre accuracy. The accuracy of the geoid height is a function of the resolution/accuracy of the input gravity and topographical data, and the methodology used to solve a geodetic boundary value problem. The purpose of this study is to estimate the maximum allowable error in the terrestrial gravity measurements based on a required standard deviation of the error in the geoid heights (e.g., ≤1cm). This is done with an assumption of a known Digital Elevation Model (DEM), and an Earth Gravitational Model (EGM) along with their error estimates.

 

We use the one-step integration method (one-step kernel) for the determination of the geoid. In this method, the anomalous gravity at any surface above the geoid is estimated by integrating over the geoid-level disturbing potentials in harmonic space. By applying the covariance law to the one-step integration method, the error of the gravity measurements at the Earth's surface can be estimated using the expected error of the geoid heights. Taking advantage of the remove-compute-restore technique, we estimate the error of the residual surface gravity measurements using the (known) error estimates of the topographical and EGM corrections.  

 

We select the Colorado test area (35°N - 40°N, 250°E - 258°E) to generate a 1¢×1¢ grid of geoid random errors with a standard deviation of 1cm. We use the topographical data from the Shuttle Radar Topography Mission (SRTM) Ver. 3.0. and the global model of DIR_R5 up to degree/order 140 to apply the remove-compute-restore technique. The uncertainty estimate of the SRTM heights and the covariance matrix of the spherical harmonic coefficients of the DIR_R5 are used to calculate the errors of the topographical gravitational attraction and low-degree EGM signals on the geoid heights and surface anomalous gravity data.

 

Our preliminary results show that to achieve a sub-centimetre accuracy in the Colorado area, we require grid surface gravity measurements with a standard deviation of less than 2.5mGal. This result is optimistic as in the geoid determination process, the anomalous gravity data are downward continued from the Earth’s surface to the geoid, whereas this step is not required in our experience. Besides, we assume a constant standard deviation of 1cm for all the errors of the geoid heights, whereas such high accuracy may not be needed in high mountains. We will provide further results for the elevation-dependent geoid error and also investigate the effect of downward continuation on our results.     
Trans-basin water vapor transport and ocean salinity changes between the Atlantic and Pacific under global warming
Authors: Sun Qiwei , Du Yan
Published: March 2022

Using the latest Coupled Model Intercomparison Projects phase 6 (CMIP6) abrupt-4xCO2 scenario, this study investigates the sea surface salinity (SSS) and hydrological cycle changes in response to global warming in the tropical Atlantic and tropical eastern Pacific. The analysis results reveal the enhancement of the global water cycle and the effect of El Niño-like sea surface temperature (SST) warming. Under global warming, the SSS decreases in the tropical Pacific and increases in the tropical Atlantic, following the “wet-get-wetter” mechanism. The increase of specific humidity leads to the enhancement of inter-basin moisture transport. More water vapor transports from the Atlantic to the Pacific in response to the rise of the freshwater flux gradient between the two basins, resulting in an SSS decrease in the Pacific and an increase in the Atlantic. At the same time, the increase of trans-basin SST gradient leads to the enhancement and westward shift of the Walker circulation, further resulting in the precipitation increase and the salinity decrease in the tropical Pacific. Furthermore, the El Niño-like warming induces a Wind-Evaporation-SST (WES) feedback in the tropical eastern Pacific. The reduced SST meridional gradient weakens the atmospheric circulation. Correspondingly, precipitation (salinity) decreases (increases) in the northeastern Pacific and increases (decreases) in the southeastern Pacific.
Contribution of gravity waves to the universal vertical wavenumber (m–3) spectra revealed by a gravity-wave permitting general circulation model
Authors: Okui Haruka , Sato Kaoru , Watanabe Shingo
Published: March 2022

Observations with high vertical resolution have shown that vertical wavenumber (m) power spectra of horizontal wind and temperature fluctuations have a universal shape with a steep slope that is roughly proportional to ~m–3. Several theoretical models explaining the universal spectra were proposed based on the assumption of gravity wave (GW) saturation. However, it has not yet been sufficiently confirmed that such characteristic spectra are fully composed of GWs. Thus, in the present study, we examine whether the m–3 spectra are due to GWs, using a GW-permitting general circulation model with a high top in the lower thermosphere. The model-simulated spectra have steep spectral slopes, which is consistent with observations. GWs are extracted as fluctuations having total horizontal wavenumbers of 21–639. From the comparison between spectra of the GWs and those of all simulated fluctuations, it is shown that GWs are dominant only at high ms, while disturbances other than the GWs largely contribute to the spectra at low ms even in the m–3 range. In addition, we examine vertical and geographical distributions of the characteristic wavenumbers, slopes, and amplitudes of GW spectra. The slopes of GW spectra are particularly steep near the eastward and westward jets in the middle atmosphere. It is theoretically shown that strong vertical shear below the jets is responsible for the formation of steep GW spectral slopes.

 

Reference:

Okui, H., Sato, K., and Watanabe, S., Contribution of gravity waves to the universal vertical wavenumber (m–3) spectra revealed by a gravity-wave permitting general circulation model, submitted to Journal of Geophysical Research Atmospheres.
Characteristics of Different Acoustic Emission Sources of Particles in Shearing Process
Authors: Liu Ziming , Jiang Yao , Lu Xingsheng
Published: March 2022

Debris flows and landslides are composed of granular materials with different grain sizes, shapes and mineral compositions. These geological hazards are complex evolutionary processes of granular structure from stable state to unstable destabilizing deformation, followed by large deformation flow. From the view of particle matter mechanics, the occurrence of these hazards is the process of the development of the particle assemblage comprising the geological body from a blocked state to a rheological state under the constraints of external boundaries. During the deformation process, the mutual collision, friction, fragmentation and structural changes between the particles will release strain energy and disperse it in the form of elastic waves, which is called acoustic emission (AE). Consequently, the characteristics of the acoustic emission signal generated during the deformation of granular materials and the changes of its parameters can be used to reflect the stability state inside the granular structure. We thus utilized three AE sensors to capture the elastic waves and investigated the relationships between characteristics of AE and mechanical behavior of granular deformation during direct shear tests with different normal stress, shear speed and grain sizes. Our results suggested that during the granular shearing process there was a strong correlation between stick-slip events and the distribution of AE characteristics. Some AE features - energy and Root Mean Square (RMS)- showed significant spatial clustering which can represent the different processes of stick-slip event. In particular, some low RMS and medium-high energy AEs represent internal local failure. And, the AE rate and B-value show a regular increase and decrease during the state of granular structure from stabilization to failure. All of them are valuable information for the prediction or early warning of geological hazards.
Modelling Hydrological Ecosystem Services of native forest for Integrated Water Resources Management on a poorly monitored basin of Central Chile
Authors: Barria Pilar , Ocampo-Melgar Anahí , Venegas Alejandro , Cerda Claudia
Published: March 2022

Ecosystem goods and services (BSE) of native forest are fundamental for water supply in Central Chile. The ongoing Megadrought (MD)- a decade lenght below normal precipitation years (~30-40%)- that affects the region, has exacerbated the water scarcity, generating a favorable scenario for the systematization and structuring of Payment for Ecosystem Services (PES) schemes in Mediterranean-climate basins of Chile. Hydrological modeling tools can be useful to support collaborative decision processes needed to implement these PES, as well as water management adaptation plans. In this context, the Chilean Water Directorate is leading the implementation of Basin Scale Strategic Water Management Plans (BSWMP) using the Water Evaluation and Planning Model (WEAP). However, the lack of biophysical data in poorly monitored basins, challenge the model implementation to quantify these ecosystem services. In this research, we used satellite data, which combined with short term field data allow us to represent the climate-forest-hydrological feedbacks and to quantify the water related ecosystem services at the sub-basin scale in the Aculeo Lake catchment, an iconic agricultural basin located in the Metropolitan region of Chile. The results indicate that there is significant impact of the MD in the native forest of the Aculeo basin, revealed by decreases in the normalized difference vegetation index and the leaf area index (~50% since year 2019), which translate into reduced evapotranspiration values. Also, according to the hydrological model, the native forest ecosystem services exacerbated during the MD, leading to increased surface runoff, infiltration rates and lake water volume storage, revealing its key role on the hydrological system. Finally, a modelling framework has been designed to support the WEAP model implementation to simulate and quantify the native forest ecosystem services at the basin scale, for poorly gauged basins, in the context of the current BSWMP.