bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Sentinel-1 and Sentinel-2 Time Series for Slangbos Encroachment Mapping in the Free State Province, South Africa
Authors: Urban Marcel , Schellenberg Konstantin , Morgenthal Theunis , Dubois Clèmence , Hirner Andreas , Gessner Ursula , Zhang Zhenyu , Mogonong Buster , Baade Jussi , Schmullius Christiane
Published: March 2021

Increasing woody cover and overgrazing in semi-arid ecosystems are known to be major factors driving land degradation. During the last decades woody cover encroachment has increased over large areas in southern Africa inducing environmental, land cover as well as land use changes. 

The goal of this study is to synergistically combine SAR (Sentinel-1) and optical (Sentinel-2) earth observation information to monitor the slangbos encroachment on arable land in the Free State province, South Africa, between 2015 and 2020. Both, optical and radar satellite data are sensitive to different land surface and vegetation properties caused by sensor specific scattering or reflection mechanisms they rely on. 

This study focuses on mapping the slangbos aka bankrupt bush (Seriphium plumosum) encroachment in a selected test region in the Free State province of South Africa. Though being indigenous to South Africa, the slangbos has been documented to be the main encroacher on the grassvelds (South African grassland biomes) and thrive in poorly maintained cultivated lands. The shrub reaches a height and diameter of up to 0.6 m and the root system reaches a depth of up to 1.8 m. Slangbos has small light green leaves unpalatable to grazers due to their high oil content and is better adapted to long dry periods compared to grass communities.

We used the random forest approach to predict slangbos encroachment for each individual crop year between 2015 and 2020. Training data were based on expert knowledge and field information from the Department of Agriculture, Forestry and Fisheries (DAFF). Several input variables have been tested according to their model performance, e.g. backscatter, backscatter ratio, interferometric coherence as well as optical indices (e.g. NDVI (Normalized Difference Vegetation Index), SAVI (Soil Adjusted Vegetation Index), EVI (Enhanced Vegetation Index), etc.). We found that the Sentinel-1 VH backscatter (vertical–horizontal/cross-polarization) and the Sentinel-2 SAVI time series information have the highest importance for the random forest classifier among all input parameters. The estimation of the model accuracy was accomplished via spatial-cross validation and resulted in an overall accuracy of above 80 % for each time step, with the slangbos class being close to or above 90 %. 

Currently we are developing a prototype application to be tested in cooperation with local stakeholders to bring this approach to the farmers level. Once field work in southern Africa is possible again, further ground truthing and interaction with farmers will be carried out.
Variations of ocean biogeochemistry in a transient deglacial simulation with MPI-ESM
Authors: Liu Bo , Six Katharina D. , Ilyina Tatiana , Extier Thomas
Published: March 2021

Variations in ocean-atmosphere carbon exchange, in response to varying physical and biogeochemical ocean states, is one of the major causes of the glacial-interglacial atmospheric CO2 changes. Most of the existing modelling studies use time-slice simulations with Earth System Models to quantify the proposed mechanisms, such as the impact of a weakened Southern Ocean westerlies and a massive discharge of freshwater from ice sheet melting on the deglacial atmospheric CO2 rise. We present the variations of ocean biogeochemistry in a transient deglaciation (21 – 10 kB.P.) simulation using the Max Planck Institute Earth System Model. We force the model with reconstructions of atmospheric greenhouse gas concentrations, orbital parameters, ice sheet and dust deposition. In line with the physical ocean component, we account for the automatic adjustment of all marine biogeochemical tracers in response to changing bathymetry and coastlines that relate to deglacial melt water discharge and isostatic adjustment. We include a new representation of the stable carbon isotope (13C) in the ocean biogeochemical component to evaluate the simulation against δ13C records from sediment cores.

The model reproduces several proposed oceanic CO2 outgassing mechanisms. First, the net primary production (NPP) in the North Atlantic Ocean dramatically decrease (by 40 – 80%) during the first melt water pulse (15 – 14 kB.P.) which is caused by the weakening in the strength of the Atlantic Meridional Overturning Circulation from 21 to 3 Sv. However, globally the oceanic NPP only slightly decreases by 8% as oceanic NPP in the South Hemisphere increases during the same period. Second, during the melt water pulse in the Southern Ocean the ventilation of intermediate waters, which has high DIC content and low alkalinity concentration, is slightly enhanced. Third, the surface alkalinity decreases due to dilution and due to episodic shifts between CaCO3 production and opal production by phytoplankton. Lastly, CO2 solubility decreases with increasing deglacial sea surface temperature. The increase of surface pCO2 caused by the above mechanisms is, however, smaller than that of the prescribed atmospheric CO2. Thus, the ocean is a weak carbon sink in this deglacial simulation.
Combining multiple arcs for orbit determination using normal equations
Authors: Mercier Flavien , Bhattacharjee Shambo , Perosanz Félix , Lemoine Jean-Michel
Published: March 2021

The normal equations are widely used to combine elementary least squares solutions, to solve very large problems which are not possible to handle directly. The principle is to reduce each problem to a minimal set of parameters present in the global problem, without removing the corresponding information, and connect them. For instance, one important application is the combination over years of daily network solutions, as performed for the ITRF (Altamimi et al., 2016) [1].

The approach can also be used in orbit determination to connect arcs solutions in order to construct the solution of a global arc. This was applied for example for GPS constellation solutions as in the article written by Beutler et al. (1996) [2]. Due to the size of the problems, it is interesting to divide for example a three days solution into three one day solutions. Another advantage is that the one day solutions are usually efficiently processed by the orbit determination software. For rapid or ultra-rapid GNSS products this is also very interesting, as the solutions are needed very often for small shifts of the global arc (for example 24 hours arcs, shifted every 6 hours in the case of ultra-rapid products). A further extension is to construct recursive solutions from these elementary arcs, leading to a filter similar to a Kalman filter.

We propose a unified methodology, associated with an efficient implementation compatible with our least squares software GINS, allowing us to solve the various problems ranging from arc connection to sequential filtering. The final objective is to construct efficient GNSS ultra-rapid products.

The application on a simple problem consisting in connecting different SLR arcs is shown, as a test case to develop and implement the methodology. In this case, the global solution can also be directly constructed for validation purposes. This study includes the construction of the solution at the end points of the elementary arcs, and also the recovery of the global solution state vectors at every epoch.

The next step will be to implement more complex parameterizations (including measurement parameters, which are not present in the SLR test case), and to apply this for GNSS constellation solutions.
Mapping the topography beneath the southern Martian polar cap using MARSIS high-resolution data
Authors: Di Silvestro Giacomo , Orosei Roberto , Guallini Luca , Morelli Andrea
Published: March 2021

The ESA Mars Express mission was launched in June 2003 and reached Martian orbit in December of the same year. Among the instruments onboard, the Italian-American radar MARSIS has retrieved valuable data, therefore contributing many discoveries related to the Red Planet, such as the evidence of sub-glacial water lakes beneath the South Pole of Mars. The technique used by this antenna is the radar echo sounding which, thanks to the electromagnetic waves emitted at frequencies in the HF range – in four separate bands centered at 1.8, 3, 4, and 5 MHz - has the ability to penetrate the ice masses, allowing the study of the internal properties and structures of glaciers and the regolith underneath.
Based on selected MARSIS radargrams, the main purpose of our analysis is to define the topography and main morphologies of the bedrock beneath Ultimi Lobe, part of the South Polar Ice Cap. Geologically speaking, this region is characterized by the South Polar Layered Deposits unit, widely showing complex layering and locally broad deformational structures (i.e., faults and folds). In particular, through the use of a georeferenced model of the bedrock surface, we focused on the search for low-topographies possibly consistent with basins able to contain the subglacial water reservoirs inferred by Orosei et al. (2018) and Lauro et al. (2020). Furthermore, we are implementing an algorithm focused on semi-automatic surface delineation using radar echo observations. Through the implementation of this script and retrieved data/images, we suggest that the machine-learning algorithm could be trained for further analysis.
Wildfire and shallows landslides: a first statistical description in Liguria (North-West Italy)
Authors: Terrone Martino , Faccini Francesco , Paliaga Guido , Solimano Monica
Published: March 2021

Rainfall-induced shallow landslides characterize most of the geomorphological phenomena occurred in Liguria (North West Italy) in the last decades: high frequency is observed between the beginning of October and the end of April, reasonably correlated with the seasonal rainfall regime.Over the years, in national and international scientific papers, the thickness of the debris cover, the poor geotechnical characteristics of the soil, the sparse forest and shrub areas, the runoff water erosion along the slope surface were identified as landslide causal factors.However, an aspect that does not seem to be considered in Liguria Region is the causal relationship between wildfires and surface landslides.The wildfire determines a series of physical and chemical changes on the slope surface, first of all the wood and shrub cover reduction. The rapid change in land use determines an increase in the run-off and a consequent soil erosion evolving into landslides.This research aims to create a first basic statistics at regional scale among landslides and wildfire, crossing different databases and inventories, estimating a trend line both in the spatial and in the temporal domain.
Disentangling controls and orbital pacing of South-East Atlantic carbonate deposition since the Oligocene (30-0 Ma)
Authors: Drury Anna Joy , Liebrand Diederik , Westerhold Thomas , Beddow Helen M. , Hodell David A. , Rohlfs Nina , Wilkens Roy H. , Lyle Mitchell W. , Bell David B. , Kroon Dick , Pälike Heiko , Lourens Lucas J.
Published: March 2021

The evolution of Cenozoic climate since 30 million years ago (Ma) has broadly chartered the transformation from a unipolar to a bipolar world. Highly resolved records of carbonate content (%CaCO3) can provide insight into regional responses to shifting climate, cryosphere and carbon cycle dynamics. Here, we generate the first South-East Atlantic %CaCO3 record spanning 30-0 Ma, derived from X-ray fluorescence (XRF) ln(Ca/Fe) data collected at Ocean Drilling Program Site 1264, located on the Angola Basin side of the Walvis Ridge (SE Atlantic Ocean). We present a comprehensive and continuous depth and age model for the entirety of Site 1264 (~316 m; 30-0 Ma), which constitutes a key reference framework for future palaeoclimatic and palaeoceanographic studies at this location.

We can identify three phases with a distinct orbital imprint on South-East Atlantic CaCO3 deposition, broadly occurring across major developments in climate, the cryosphere and/or the carbon cycle: 1) strong ~110 kyr eccentricity pacing prevails during Oligo-Miocene global warmth (~30-13 Ma); 2) eccentricity-modulated precession imprints more strongly after the mid Miocene Climate Transition (mMCT) (~14-8 Ma); 3) strong obliquity pacing prevails in the late Miocene (~7.7-3.3 Ma) following the increasing influence of high-latitude processes.

The lowest %CaCO3 (92-94%) occur between 18.5-14.5 Ma, potentially reflecting increased dissolution or decreased productivity, probably caused by widespread early Miocene warmth. Around 14 Ma, the increased sensitivity to precession at Site 1264 is associated with an increase in mass accumulation rates (MARs) and could reflect increased regional CaCO3 productivity and/or an influx of less corrosive deep water following regional changes in surface and/or deep-water circulation after Antarctic reglaciation across the mMCT.

The highest %CaCO3 and MARs indicate the late Miocene Biogenic Bloom (LMBB) occurs between ~7.8-3.3 Ma at Site 1264, which is broadly, but not exactly, contemporaneous with the LMBB in the equatorial Pacific Ocean. Global similarities in the expression of the LMBB may reflect an increased nutrient input into the global ocean resulting from enhanced aeolian dust and/or glacial/chemical weathering fluxes, whereas regional variability in the timing and amplitude of the LMBB may be driven by regional differences in cooling, continental aridification and/or changes in ocean circulation during the latest Miocene.
Extreme waves and surges interaction with tides during storms in winter 2013/2014.
Authors: Rulent Julia
Published: March 2021

The interaction between waves, surges and tides is one of the main drivers of coastal total water levels (TWL).  Understanding this interaction is crucial for studying high TWL formation near shore, and to do this it is important to not only evaluate how high the TWL is but also when and where it occurs.

In this study we use a high resolution (1.5 km) three-way coupled (waves-atmosphere-ocean) numerical model developed by the MetOffice (UKC4) to study coastal conditions at the UK coast during the extreme events of winter 2013, which was chosen as case study because of the amount of flooding that occurred in relation to storms and surges during this period.

For each coastal grid point the ten strongest storms of that winter, ranked by the significant wave height (Hs) magnitude, were selected. During these storm periods, the number of hours in which Hs and surges exceeded the 90th percentile of winter 2013 were evaluated considering what tidal stage they occurred on. The same was done for instances where high Hs and surges occurred simultaneously. The aim is to understand if specific areas were predominantly affected by one of the TWL components and how Hs and surges interacted with the tide. What was the spatial distribution of the waves, surges, and tides during winter 2013? Did extreme Hs and Surges occur more often over specific stages of the tidal cycle? Did they occur simultaneously? 

In this study we show that during the winter 2013, Hs and surges above the 90th percentile value did occur simultaneously at all stages of the tidal cycle. They more often occurred together over the rising tide with in average 8.7% and 8.6% of instances found two and three hours before high tide. In 7.7% of cases high wave and surges also concurred at high tide.
Detection of possible seismic station phase reversals using parametric data from seismological bulletins
Authors: Lentas Konstantinos
Published: March 2021

A simple and fast technique to detect systematic changes in the performance of seismic stations by using parametric data is being presented. The methodology is based on a simple principal, notably, quantifying the goodness of fit of first motion manually picked polarities from seismological bulletins versus available earthquake mechanism solutions over time. The probability of the reporting polarity data fitting (and not fitting) source mechanisms is quantified by calculating the probability distribution of several Bernoulli trials over a randomly perturbed set of hypocentres and velocity models for each earthquake mechanism - station polarity combination. The method was applied to the registered seismic stations in the bulletin of the International Seismological Centre (ISC) after grouping each polarity pick by reporting agency, using data from the past two decades. The overall agreement of first motion polarities against source mechanisms is found to be good with a few cases of seismic stations showing indications of systematic phase reversals over certain time periods. Specifically, results were obtained for 50% of the registered stations at the ISC, and from these stations 70% show reliable operation during the operational time period under investigation, with only 3% showing the opposite, and 7% showing evidence of systematic changes in the quality of the reported first motion polarities. The rest showed great variability over short periods of time, which does not allow one to draw any conclusions. Comparing waveform data with the associated reported polarities revealed a mixture of cases of either questionable picking or true station phase reversals.
A quasi-operational air quality forecasting system for the contiguous United States (CONUS) 
Authors: Kumar Rajesh , Pfister Gabriele , Bhardwaj Piyush
Published: March 2021

We present a research system for regional air quality forecasting over  the contiguous United States (CONUS). This system has been developed at the National Center for Atmospheric Research (NCAR) to support community model development, allow early identification of model errors and biases, and support the atmospheric science community in their research. At the same time, it assists field campaign planning and air quality decision-making. The forecasts aim to complement the operational air quality forecasts produced by the National Oceanic and Atmospheric Administration (NOAA) and not to replace them. A publicly available information dissemination system has been established that displays various air quality products including a near-real-time evaluation of the model forecasts. Our forecasting system has been producing a 48-h forecast every day at 12 km x 12 km grid spacing over the entire CONUS since June 2019 and at 4 km x 4 km grid spacing in Colorado since June 2020. Here, we will report on the performance of our air quality forecasting system in simulating meteorology, PM2.5, ozone, and NOx for the period of 1 June 2019 to 31 December 2020. Our system showed excellent skill in capturing hourly to daily variations in temperature, surface pressure, relative humidity, water vapor mixing ratios, and wind direction but showed, in parts, relatively larger errors in wind speed. The model captured the seasonal cycle of surface PM2.5 and ozone very well in different regions of CONUS and at different types of sites (urban, suburban, and rural) but generally overestimates summertime surface ozone and fails to capture very high surface PM2.5 events. These shortcomings are being addressed in current work. The skill of the air quality forecasts remains fairly stable between the first and second days of the forecasts. Our air quality forecast products are publicly available at https://www.acom.ucar.edu/firex-aq/forecast.shtml and we invite the community to use our forecasting products for their research, as input for urban scale (< 4 km) air quality forecasts, or the co-development of customized products just to name a few applications.
Impacts of Stratospheric Ozone Extremes on Arctic High Cloud
Authors: Smith Karen , Maleska Sarah , Virgin John
Published: March 2021

Stratospheric ozone depletion in the Antarctic is well known to cause changes in Southern Hemisphere tropospheric climate; however, because of its smaller magnitude in the Arctic, the effects of stratospheric ozone depletion on Northern Hemisphere tropospheric climate are not as obvious or well understood. Recent research using both global climate models and observational data has determined that the impact of ozone depletion on ozone extremes can affect interannual variability in tropospheric circulation in the Northern Hemisphere in spring. To further this work, we use a coupled chemistry–climate model to examine the difference in high cloud between years with anomalously low and high Arctic stratospheric ozone concentrations. We find that low ozone extremes during the late twentieth century, when ozone-depleting substances (ODS) emissions are higher, are related to a decrease in upper tropospheric stability and an increase in high cloud fraction, which may contribute to enhanced Arctic surface warming in spring through a positive longwave cloud radiative effect. A better understanding of how Arctic climate is affected by ODS emissions, ozone depletion, and ozone extremes will lead to improved predictions of Arctic climate and its associated feedbacks with atmospheric fields as ozone levels recover.
Shifts in Herring and Mackerel Resources in the Northeast Atlantic under Global Warming
Authors: Zeng Yuanzhuo
Published: March 2021

Global warming is one of the most imminent challenges facing humanity in the 21st century. It will not only have a profound effect on ecosystems but also on economies around the world. The shift in habitats of economically important marine species caused by rising seawater temperatures will bring challenges to the existing fishing industry, especially small fishing businesses. This research tries to build mathematical models to find out shifts in herring and mackerel resources in the Northeast Atlantic under global warming, and offer advice on how to deal with potential development challenges.

First, several models are designed to predict the change in seawater temperature over the next 50 years. We base our prediction model on the Coupled Model Intercomparison Project Phase 6 (CMIP6) and conduct a detailed analysis of different possible levels of seawater temperature increases caused by different carbon emissions levels. Then the lifecycles and migration behavior of herring and mackerel are researched and the influence of seawater temperature increases on their ecosystems is predicted and charted. The tendency of herring and mackerel populations going further offshore and northerly is obvious.

Second, after analyzing the migration of fish populations, we research the fishing industry in the region and deem it necessary for small fishing companies to make adjustments to their fishing methods. If global warming follows the relatively moderate economic development model, which is the most likely scenario, fish populations will too far away for small fishing companies to harvest near 2091. Our suggested strategy is that fishing vessels capable of operating without land-based support should be increased so that they can operate in waters further from the coast to maintain the harvest.

Finally, the models’ sensitivity is tested, and the results demonstrate the effectiveness and robustness of our modeling. This research provides insights into how small fishing companies should relocate themselves to optimize their business, in order to deal with long-term development challenges, and seize the opportunity in fishing under the effects of Global Warming.
Debris flow impacts on infrastructure: analyzing the database of accidents 
Authors: Petrova Elena
Published: March 2021

The presentation considers natural-technological accidents that were triggered by the impacts of debris flows on infrastructure facilities. As input data, the information collected in the author's database of natural-technological accidents and emergencies that occurred in the Russian Federation from 1991 to 2020 was used. Based on the statistical and geographical analysis of the data, the main types of natural-technological accidents caused by the impact of debris flows have been identified. Various linear structures are mostly exposed to the debris flows. The most vulnerable to the debris flow impacts are facilities of the transportation infrastructure, as well as power lines, pipelines, and other lines of communication. During the above period under consideration, road and railway accidents, traffic disruptions, accidents in power, warm, water, and gas supply systems caused by debris flows were registered in the database. Natural-technological accidents and emergencies due to debris flow impacts on the infrastructure were recorded in the Far East of the Russian Federation including Sakhalin and Magadan Regions, and Primorsky Territory, as well as in the Republics and Territories of the North Caucasus. The long-term average frequency of their occurrences was estimated; their seasonal distribution was investigated. The proportion of natural-technological accidents caused by the impact of debris flows, in the total number of events caused by other adverse and hazardous natural processes and phenomena, is relatively small. However, the potential danger of such impacts must be taken into account when constructing transportation and other lines of communications, especially in areas of increased risk of debris flows.
Assessing the impacts of climate variability and human activities on runoff with a nonlinear hybrid model
Authors: Qin Yanhua , Sun Xun , Li Baofu , Merz Bruno
Published: March 2021

Understanding the contributions of potential drivers on runoff is of great importance for the sustainable management of water resources. In this study, we develop a nonlinear hybrid model, which integrates extreme-point symmetric mode decomposition (ESMD), back propagation artificial neural networks (BPANN) and weights connection method, to represent the relationships between different drivers and runoff. ESMD allows to decompose the times series of drivers and runoff into different components. BPANN is then employed to simulate the relationship between the drivers and runoff at each time scale separately. The performance of this model is compared with multiple linear regression (MLR). We select the mountainous area of the Hotan River Basin as case study area. The results indicated that runoff exhibits oscillation periods of 2, 9 and 14 years. Climate variability strongly affects runoff and accounts for 81% of the runoff variation, while human activities play a minor role, accounting for 8%. In all performance measures, the proposed model substantially outperforms MLR. The proposed model can represent nonlinear relations and simulate the association between drivers and runoff at different time scales (even opposite associations), which is the improvement of this study.
A mechanistic model for bedrock undercut from saltating bedload particle impacts
Authors: Li Tingan , Venditti Jeremy , Sklar Leonard
Published: March 2021

Bedrock walls can be undercut by saltating bedload particle impacts that are deflected by alluvial cover. Continued undercutting of the lower wall creates an imbalance on the wall and may cause the upper part to collapse and to widen the whole channel. Compared with vertical erosion rates, less is known about lateral erosion (undercutting) rates that are thought to dominate when river beds are alluviated. Here, we derive an analytical model for lateral erosion by saltating bedload particle impacts. The analytical model is a simplification of the Li et al. (2020) numerical model of the same process. The analytical model predicts a nonlinear dependence of lateral erosion rate on sediment supply, shear stress and grain size, revealing the same behaviour observed in the numerical model, but without tracking particle movements through time and space. The analytical model considers both uniformly distributed cover and patchy partial cover that is implemented with a fully alluviated patch along one bank and a bare bedrock along the other. The model predicts that lateral erosion rate peaks when the bed is ~70% covered for uniformly distributed alluvium and when the bed is fully covered for patchy alluvium. Vertical erosion dominates over lateral erosion for ~75% and >90% of sediment supply and transport conditions for uniformly distributed cover and patchy cover, respectively. We use the model to derive a phase diagram of channel responses (steepening, flattening, narrowing, widening) for various combinations of transport stage and relative sediment supply. Application of our model to Boulder Creek, CA captures the observed channel widening in response to increased sediment supply and steepening in response to larger grain size.
Air-sea strongly coupled data assimilation for tropical cyclone prediction
Authors: Chen Xingchao
Published: March 2021

Air-sea interactions are critical to tropical cyclone (TC) energetics. However, oceanic state variables are still poorly initialized, and are inconsistent with atmospheric initial fields in most operational coupled TC forecast models. In this study, we first investigate the forecast error covariance across the oceanic and atmospheric domains during the rapid intensification of Hurricane Florence (2018) using a 200-member ensemble of convection-permitting forecasts from a coupled atmosphere-ocean regional model. Meaningful and dynamically consistent cross domain ensemble error correlations suggest that it is possible to use atmospheric and oceanic observations to simultaneously update model state variables associated with the coupled ocean-atmosphere prediction of TCs using strongly coupled data assimilation (DA). A regional-scale strongly coupled DA system based on the ensemble Kalman filter (EnKF) is then developed for TC prediction. The potential impacts of different atmospheric and oceanic observations on TC analysis and prediction are examined through observing system simulation experiments (OSSEs) of Hurricane Florence (2018). Results show that strongly coupled DA resulted in better analysis and forecast of both the oceanic and atmospheric variables than weakly coupled DA. Compared to weakly coupled DA in which the analysis update is performed separately for the atmospheric and oceanic domains, strongly coupled DA reduces the forecast errors of TC track and intensity. Results show promise in potential further improvement in TC prediction through assimilation of both atmospheric and oceanic observations using the ensemble-based strongly coupled DA system.
Advancing the cyberinfrastructure for smart water metering: A new open source water end use disaggregation algorithm
Authors: Attallah Nour , Horsburgh Jeffery , Bastidas Pacheco Camilo
Published: March 2021

Water end use disaggregation aims to separate household water consumption data collected from a single residential water meter into appliance/fixture-level consumption data. In recent years, the field has rapidly expanded as the value of disaggregated data has been shown for understanding water use behavior, identifying anomalies, and identifying opportunities for conserving water. Several methods have been developed for disaggregating water end uses from high temporal resolution water use data collected using residential smart water meters. However, most existing methods have been incorporated into proprietary software tools and have been tested using datasets that are inaccessible due to privacy issues, with the result being that neither the code nor the data from these studies are available for verification or potential reuse. We describe and demonstrate a new, open source, and reproducible water end use disaggregation and classification tool that builds upon the results of existing smart water metering and end use disaggregation studies. The tool was designed and developed in Python and can be accessed via any current Python programming environment. It was tested on anonymized, high temporal resolution datasets collected from 31 residential dwellings located in the Cities of Logan and Providence, Utah, USA for a period of one month. Results from different meter types and sizes were tested to demonstrate the accuracy and reproducibility of the tool in disaggregating and classifying high temporal resolution data into individual water end use events. Execution of the tool requires approximately one minute for processing one-day of data collected at a four second time interval for one dwelling. The disaggregation tool is open source and can be adapted to specific research needs. The anonymized dataset we used to develop and test the tool is openly available in the HydroShare data repository.
Comparison among Gravimetric, Astrogravimetric and Astrogeodetic Geoids: Case Study for Austria
Authors: Abd-Elmotaal Hussein , Kühtreiber Norbert
Published: March 2021

It is used to state that all geoid determination techniques should yield to the same geoid if the indirect effect is properly taken into account (Heiskanen and Moritz, 1967). The current study compares different geoid determination techniques for Austria. The used techniques are the gravimetric, astrogravimetric and astrogeodetic geoid determination techniques. The available data sets (gravity, deflections of the vertical, height, GPS) are described. The window remove-restore technique (Abd-Elmotaal and Kuehtreiber, 2003) has been used. The available gravity anomalies and the deflections of the vertical have been topographically-isostatically reduced using the Airy isostatic hypothesis. The reduced deflections have been used to interpolate deflections on a relatively dense grid covering the data window. These gridded reduced deflections have been used to compute an astrogeodetic geoid for Austria using least-squares collocation technique within the remove-restore scheme. The Vening Meinesz formula has been used to compute an astrogravimetric geoid for Austria. Another gravimetric geoid for Austria has been determined in the framework of the window remove-restore technique using Stokes integral with modified Stokes kernel. All computed geoids have been validated using GNSS/levelling derived geoid. A wide comparison among the derived geoids computed within the current investigation has been carried out.
Integrated Platform for Smart Operational Monitoring and Efficient Energy Management of Water Supply Networks
Authors: Perdios Anastasios , Papacharalampous Georgia , Dimas Athanasios , Horsch Georgios , Karathanasi Irene , Katrivesis Fotis , Stergiopoulos Demetris , Zarkadoula Maria , Zappa Eleftheria , Koutsogianni Olga , Alexandrou Vasileios , Pappas Theodoros , Paraskevopoulos Pavlos , Venizelos Athanasios , Langousis Andreas
Published: March 2021

Research project “PerManeNt” aims at developing an integrated platform for operational monitoring, smart control, and sustainable energy management of the external aqueduct system of the city of Patras in western Greece, which consists of more than 60 km of pressurized pipeline, 44 pumping wells, 3 springs, 22 regulating tanks, and 14 pumping stations. Given the significance of the existing infrastructure, 5 main pipelines, 7 pumping wells, 9 reservoirs, and 5 pumping stations were selected to be monitored in the context of: a) real-time data collection, processing and visualization, b) near real-time detection of system malfunctioning and automatic alarm generation, and c) generation of short and longer term forecasts for the water demand and corresponding energy consumption rates, based on hydrometeorological data and environmental indices. The development of the integrated platform is expected to have significant scientific, financial, societal and environmental impacts including: i) efficient water resources management and environmental protection, ii) reduction of the operational costs and regulator expenses for system maintenance and management, iii) promotion of citizens’ awareness regarding environmental issues, and iv) significant improvement of the quality of services offered, including pricing and emergency planning.

Acknowledgments:

This research is co‐financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH – CREATE – INNOVATE (project code: T2EDK-4177.
Development of tools to assess and mitigate the impacts of peat harvesting on aquatic ecosystems
Authors: St-Hilaire André , Duchesne Sophie , Fortin Claude , Hafdi Sabiha , Bettis Hermine , Khadri Moez
Published: March 2021

Peat harvesting in an important industry in northern Europe and in North America. In Canada peat is harvested to be used as a horticulture substrate. The harvesting is generally done by vacuuming the thin dried upper layer of peat found below the acrotelm, after removing the latter and draining the water. Drained water is typically routed to settling basins prior to being released in neighbouring natural water courses. This communication summarizes our research efforts to develop tools to optimize settling pond design and minimize suspended sediment loads and to provide the industry with means to assess the health of aquatic ecosystems that receive the drained water.

Current settling pond designs are based on simple rules of thumb (e.g. 25 m3/ha of harvested peatland). In our study, a hydraulic model was used to test different basin configurations (basins with and without weirs at the outlet, basins in series, basins equipped with a geotextile curtain). It was found that while the trapping efficiency was not significantly improved by adding a second basin compared to a single one, adding a geotextile curtain improved the trapping of coarser sediments. Our results moreover showed that fine sediments deposited during low flow periods, in the downstream end of the basins, could be easily resuspended during and after rainfall events, thus showing the importance of frequent maintenance. There are also some strong indications that wind erosion could be a major source of sediments in the drainage water.

Different indicators of stream ecosystem health were compared to quantify the impact of peat harvesting on the receiving water bodies. They included 1) using fish abundance and species richness; 2) quantifying sediment deposition and its organic content; 3) determining ionic composition of effluents and receiving waters; and 4) developing a water quality index (WQI) based on multiple physico-chemical measurements (ammonia, conductivity, pH and suspended sediment concentrations). The developed WQI was shown to be the most promising indicator of ecosystem health and allows for a simple classification of water quality downstream of the confluence between the drain outlet and the receiving stream.
Opposite trends of sea-breeze speeds and gusts in Eastern Iberian Peninsula, 1961-2019
Authors: Bedoya-Valestt Shalenys , Azorin-Molina Cesar , Guijarro José A. , Sanchez-Morcillo Victor J.
Published: March 2021

Long-term trends of local winds such as sea breezes have been less addressed in climate research, despite their impacts on broad environmental and socioeconomic spheres, such as weather and climate, agriculture and hydrology, wind-power industry, air quality or even human health, among many others. In a warming climate, sea breezes could be affected by changes on air temperature, as these onshore winds are thermally-driven by gradients between the sea-land air, but also by ocean-atmosphere oscillations or changes in large-scale atmospheric circulation. In the last few decades, advances in wind trends studies evidenced a recovery in global wind stilling during the last 10 years, and differences in the sign-magnitude of wind speed trends were found at seasonal-scale, suggesting the hypothetic effect of the reinforcement of local wind circulations in the warm seasons.

In this study, we analyze for the first time the long-term trends, multidecadal variability and possible drivers of the sea-breeze speeds and gusts in Eastern Iberian Peninsula during the last 58 years (1961-2019), using homogenized wind speed and gusts data from 16 meteorological stations. To identify potential sea breeze episodes, we developed a robust automated method based on alternative criteria. Our results suggest a decoupling between the declining sea-breeze speeds and the strengthening of the maximum gusts for much of the 1961-2019 period at annual, seasonal and monthly scales, but differences based on locations were also found. Because sea breeze changes can be driven by multiple complex factors (i.e. land use changes, land-sea air temperature gradient, complex orography, etc.), the attribution of causes is challenging. To better understand the causes behind the opposite trends between sea-breeze speeds and gusts, we investigate the effect of e.g. the changes in large-scale atmospheric circulation or physical-local factors.
Samalas and the Fall of the Mongol Empire:  A volcanic eruption’s influence on the dissolution of history’s largest contiguous empire
Authors: Kern Zoltán , Pow Stephen , Pinke Zsolt , Ferenczi László
Published: March 2021

Climate responses to major tropical volcanic eruptions bring about complex social effects with lasting historical consequences. Based on several historical episodes, we establish an argument that the weather-altering eruption of Samalas (1257), which shifted the Asian monsoon and caused global weather anomalies, may have played a significant role in the breakup of the Mongol Empire. The empire’s end came soon after the largest eruption of the Common Era, and its political situation devolved into open warfare between claimants to the throne. While this has previously been described in the historiography as a purely political series of events guided by individual actors’ motivations, the state’s collapse occurred in fact amidst a series of epidemics, droughts, famines, and erratic weather which can be plausibly tied to aftereffects of the eruption. 

 

Focusing on a few case studies, textual sources mention a fatal epidemic in southwestern China in 1259 which suddenly ended the life of Möngke Khan, the last ruler of the unified Mongol Empire. Based on terminology and descriptions of the epidemic, records of cholera across the larger region, and an ostensible relationship between other historical mega eruptions and ensuing pandemics, we argue that 1259 may have seen a cholera outbreak. Secondly, we note that the hydroclimatic aftereffect of extreme drought over Mongolia and Eastern China, peaking in 1259-60, weakened cavalry forces based in Inner Asia and the Mongolian Plateau. The drought and resultant famine had major historical consequences by influencing the outcome of the civil war (1259–1264) fought between Möngke Khan’s surviving brothers for control of the empire. Mongolia lost its undisputed central position as the state fragmented into at least six independent khanates, marking the end of the unified Mongol Empire. While political events and human decisions played major roles in developments, and societal responses could ameliorate the Samalas eruption’s impact, we argue that ignoring it leaves out an important element of our understanding of these events of global historical significance. The work of the researchers is presently being prepared for publication.
A sanity check for earthquake recurrence models used in PSHA of slow deforming regions: the case of SW Iberia
Authors: Ramalho Margarida , Matias Luis , Neres Marta , M. C. Carafa Michele , Carvalho Alexandra , Teves-Costa Paula
Published: March 2021

Probabilistic Seismic Hazard Assessment (PSHA) is the most common tool used to decide on the acceptable seismic risk and corresponding mitigation measures. One key component of these studies is the earthquake generation model comprising the definition of source zones and recurrence relationships. Slow deforming regions are particularly challenging for PSHA since the inferred return period for large earthquakes is longer than the instrumental and historical seismicity records, and the relationship between known or probable active faults and seismicity is uncertain. Therefore, in these areas PSHA results show a large variability that impairs its acceptance by the political decision-makers and the public in general. We propose two consistency tests to address the variability of earthquake generation models found in PSHA studies: i) one rule-of-thumb test where the seismic moment release from the model is converted to an average slip on a typical fault and compared with known plate kinematics or GNSS deformation field; ii) using a neotectonic model, the computed deformation is converted into seismic moment release and to a synthetic earthquake catalogue. We apply these tests to the W and SW Iberia slow deforming region, where two earthquake source areas are investigated: 1) the Lower Tagus Valley, one of the largest seismic risk zones of Portugal; and 2) the offshore SW Iberia area, considered to be the source for the 1st November 1755 event (M~8.7). Our results show that some of the earthquake source models should be regarded as suspicious, given their high/low moment release when compared to the expected values from GNSS observations or neotectonic modelling. In conclusion, PSHA studies in slow deforming regions should include a similar sanity check on their models’ evaluation, downgrading the weight of poorly compliant models.
Effects of the Background Turbulence on the Relaxation of Ion Temperature Anisotropy in Space Plasmas
Authors: Moya Pablo S , Navarro Roberto E
Published: March 2021

Turbulence in space plasmas usually exhibits two regimes separated by a spectral break that divides the so called inertial and kinetic ranges. Large scale magnetic fluctuations are dominated by MHD non-linear wave-wave interactions following a -5/3 or -3/2 slope power-law spectrum. After the break, at scales in which kinetic effects take place, the magnetic spectrum follows a steeper power-law k- α shape given by a spectral index α > 5/3. The location of the break and the particular value of α, depend on plasma conditions, and different space environments can exhibit different spectral indices. Despite its ubiquitousness, the possible effects of a turbulent background spectrum in the quasilinear relaxation of solar wind temperatures are usually not considered. In this work, a quasilinear kinetic theory is used to study the evolution of the proton temperatures in a solar wind-like plasma composed by cold electrons and bi-Maxwellian protons, in which electromagnetic waves propagate along a background magnetic field. Four wave spectrum shapes are compared with different levels of wave intensity. We show that a sufficient turbulent magnetic power can drive stable protons to transverse heating, resulting in an increase in the temperature anisotropy and the reduction of the parallel proton beta. Thus, stable proton velocity distribution can evolve in such a way as to develop kinetic instabilities. This may explain why the constituents of the solar wind can be observed far from thermodynamic equilibrium and near the instability thresholds.