bluuebunny/crossref_metadata_2025 huggingface dataset:
A blueprint for thermodynamically consistent box models and a test bed for thermodynamic optimality principles
Authors: Schymanski Stan , Westhoff Martijn
Published: March 2020

Thermodynamic optimality principles, such as maximum entropy production or maximum power extraction, hold a great promise to help explain self-organisation of various compartments of planet Earth, including the climate system, catchments and ecosystems. There is a growing number of examples for more or less successful use of these principles in earth system science, but a common systematic approach to the formulation of the relevant system boundaries, state variables and exchange fluxes has not yet emerged. Here we present a blueprint for the thermodynamically consistent formulation of box models and rigorous testing of optimality principles, in particular the maximum entropy production (MEP) and the maximum power (MP) principle. We investigate under what conditions these principles can be used to predict energy transfer coefficients across internal system boundaries and demonstrate that, contrary to common perception, these principles do not lead to similar predictions if energy and entropy balances are explicitly considered for the whole system and the defined sub-systems. We further highlight various pitfalls that may result in thermodynamically inconsistent models and potentially wrong conclusions about the implications of thermodynamic optimality principles. 
The analysis is performed in an open source mathematical framework, using the notebook interface Jupyter, the programming language Python, Sympy and a newly developed package for Python, "Environmental Science using Symbolic Math" (ESSM, https://github.com/environmentalscience/essm). This ensures easy verifiability of the results and enables users to re-use and modify variable definitions, equations and mathematical solutions to suit their own thermodynamic problems. 
2.5 years of TROPOMI S5P total ozone column data: geophysical global ground-based validation and inter-comparison with other satellite missions
Authors: Garane Katerina , Koukouli Maria-Elissavet , Verhoelst Tijl , Lerot Christophe , Heue Klaus-Peter , Balis Dimitrios , Redondas Alberto , Pazmino Andrea , Bazureau Ariane , Romahn Fabian , Zimmer Walter , Xu Jian , Lambert Jean-Christopher , Loyola Diego , Van Roozendael Michel , Goutail Florence , Pommereau Jean-Pierre
Published: March 2020

The Sentinel-5 Precursor (S5P) mission, launched in October 2017, carries the TROPOspheric Monitoring Instrument (TROPOMI), which provides a daily global coverage at a spatial resolution as high as 5.5 km x 3.5 km and will extend the European atmospheric composition record initiated with GOME/ERS-2 in 1995. Due to the ongoing need to understand and monitor the recovery of the ozone layer, as well as the evolution of tropospheric pollution, ozone remains one of the leading species of interest during this mission.

In this work, two and a half years of TROPOMI near real time (NRTI) and offline (OFFL) total ozone column (TOC) products are presented and compared to daily and individual, globally distributed, ground-based quality assured Brewer and Dobson TOC measurements. The daily ground-based ozone measurements used here are deposited in the World Ozone and Ultraviolet Radiation Data Centre (WOUDC). The individual Brewer measurements are made available by the European Brewer Network (Eubrewnet). Furthermore, twilight zenith-sky measurements obtained with ZSL-DOAS (Zenith Scattered Light Differential Optical Absorption Spectroscopy) instruments, which form part of the SAOZ network (Système d’Analyse par Observation Zénitale), are used for the validation.

The quality of the TROPOMI TOC data is evaluated in terms of the influence of various geophysical quantities such as location, solar zenith angle, viewing angle, season, effective temperature, surface albedo and clouds. The overall statistical analysis of the global comparison shows that the mean bias and the mean standard deviation of the percentage difference between TROPOMI and ground-based TOC is within 0 –1.5% and 2.5 %–4.5 %, respectively. Moreover, based on the full available dataset, a first attempt is made for a drift investigation.

Additionally, the TROPOMI OFFL and NRTI products are evaluated against already known spaceborne sensors, namely, the Ozone Mapping Profiler Suite, on board the Suomi National Polar-orbiting Partnership (OMPS/Suomi-NPP), NASA, and the Global Ozone Monitoring Experiment 2 (GOME-2), on board the Metop-A (GOME-2/Metop-A) and Metop-B (GOME-2/Metop-B) satellites. This analysis shows a very good agreement for both TROPOMI products with well-established instruments, with the absolute differences in mean bias and mean standard deviation being below +0.7% and 1%, respectively.
Observed evaporation dynamics from a large lowland reservoir during a hot summer
Authors: Jansen Femke A. , Teuling Adriaan J. , Jacobs Cor M.J. , Hazenberg Pieter
Published: March 2020

In the past, most field studies on evaporation have focussed on land-atmosphere interactions, while the turbulent exchange above inland water surfaces have remained underexposed. However, due to the differences in characteristics of a land surface and a water body there are other driving mechanisms underlying the process of evaporation. This results in a difference in dynamics of surface evaporation between the land use types and consequently should lead to a different parameterization in hydrological models. Especially in a changing climate the importance of having an understanding of the driving mechanisms of open water evaporation (E­water) becomes more crucial to better predict to what extent the quantity and dynamics of Ewater could change in the future. This is essential to improve the parameterization of Ewater in operational hydrological models and therefore to optimize water management now and in the future. For this purpose, we set-up a long-term measurement campaign to measure Ewater and related meteorological variables over a large lowland reservoir in the Netherlands.

During the hot summer of 2019 two eddy-covariance systems were operational around lake IJsselmeer in the Netherlands. These high-temporal measurements are used to study the dynamics and to identify the forcing mechanisms of Ewater. We present the turbulent heat flux dynamics at several temporal scales over the summer season of 2019 and show how they are related to potential drivers and parameters. From this we develop a simple data based model for estimating hourly Ewater rates. Additionally, we compare Ewater resulting from the direct measurements to Ewater derived from commonly used evaporation models. Furthermore, we investigate and discuss the effect of including spatial variability on the total water loss of the IJsselmeer through Ewater. We achieve this by using the skin water temperature, which is considered an important predictor in the estimation of Ewater. Therefore, we use satellite products containing this information to extrapolate the in-situ observations towards spatially distributed rates of Ewater.
The dramatic variability of cations impacts on Fe speciation in Fe-OM nanoaggregates
Authors: Vantelon Delphine , Beauvois Anthony , Jestin Jacques , Davranche Mélanie
Published: March 2020

Natural colloids composed of iron (Fe) and organic matter (OM) are a key factor controlling metallic pollutants mobility according to their high adsorption capacities, consequence of their high binding sites density. The physico-chemical condition in which the Fe-OM nanoaggregates are formed influences their structural organization, and more specifically the Fe speciation. In this study, we probe the influence of three major cations, present in high quantity in natural systems: Calcium (Ca), Aluminum (Al) and Silicon (Si). Ca is known to have a huge affinity toward OM, as well as Al which also easily get into Fe hydroxides structure. For its part, Si is known to restrain Fe oxides growth and crystallinity, despite mechanisms remain unknown. Ca, Al and Si are thus expected to modify Fe-OM nanoaggregates organization and impact Fe speciation.

Mimetic environmental Fe-OM-cation nanoaggregates were synthesized with different Fe/OM and cation/Fe ratios. They were observed by TEM. The Fe speciation was characterized by XAS as well as the cations interactions with the components of the Fe-OM colloids. The size and arrangement of Fe-nanoparticles were determined by SAXS. Results show that Fe speciation is complex and variable according to Fe and cation contents relative to OM. Fe phases appear to be composed of oligomers and ferrihydrite nanoparticles, both embedded in the OM matrix. The Fe-nanoparticles are forming a fractal network which organization is controlled by the OM. When the Fe/OM ratio increases, oligomers content decreases to the benefit of Fe-nanoparticles which size increases. Adding cations, this phenomenon is strongly modified, either increased, with the addition of Ca and Al, or decreased, with the addition of Si. These modifications result from the different interactions we could evidence between the cations and the different Fe-OM network components.

These results clearly highlight the dramatic effect of Al, Si and Ca cations on the Fe-OM colloidal network, impacting both Fe speciation and OM organization. These structural modifications directly impact the capabilities of Fe-OM nanoaggregates to trap and transport pollutants.
Ice mass change in the Amur Drainage Basin estimated from multi-source observations
Authors: Xu Zhiming , Wang Zhengtao
Published: March 2020

The Amur River, with a total length of 4440 kilometers, is one of the major Asian rivers as well as the tenth largest river in the world flowing through China, Mongolia and Russia. As one of the high latitude rivers, the characteristics of terrestrial water storage(TWS) in Amur Drainage Basin are different from those in the middle and low latitude rivers. Its runoff is influenced by precipitation as well as the ice melt water, in this case, the research on this region has a unique scientific significance. In this study, Gravity Recovery and Climate Experiment(GRACE) time-varying gravity data is used to inverse the change of TWS in order to study the seasonal and interannual change of water storage in Amur Drainage Basin. By introducing Global Land Data Assimilation System(GLDAS) hydrological model and Global Precipitation Measurement(GPM) precipitation data, we can get the mass change of ice and snow of this area with water balance method. The result shows that the mass change of ice and snow detected by GRACE fits well with the trend of temperature. Which means GRACE combined with multi-source data has the ability to detect the change of ice and snow in high latitude rivers during the ice age.
Dynamical evolution of the seismic coda wave increments during the 2011-2012 Santorini's caldera unrest. A Non-Extensive Statistical Physics approach.
Authors: Aspiotis Theodoros , Koutalonis Ioannis , Michas Georgios , Valianatos Filippos
Published: March 2020

Santorini's caldera being unrest during 2011-2012, led several studies to raise the important question of whether seismicity is associated with an impending and potential volcanic eruption or it solely relieves the accumulated tectonic energy. In the present work we study seismic coda waves generated by local earthquake events prior, during and after the seismic crisis that occurred within the caldera area. Coda waves are interpreted as scattered seismic waves generated by heterogeneities within the Earth, i.e. by faults, fractures, velocity and/or density boundaries and anomalies, etc. In particular, we utilize the three components of the seismograms recorded by three seismological stations on the island of Santorini and estimate the duration of the coda waves by implementing a three step procedure that includes the signal-to-noise ratio, the STA/LTA method and the short time Fourier transform. The final estimation was verified or reestimated manually due to the existent ambient seismic noise. Due to the nature and the path complexity of the coda waves and towards achieving a unified framework for the study of the immerse geo-structural seismotectonic complexity of the Santorini volcanic complex, we use Non-Extensive Statistical Physics (NESP) to study the probability distribution functions (pdfs) of the increments of seismic coda waves. NESP forms a generalization of the Boltzmann-Gibbs statistical mechanics, that has been extensively used for the analysis of semi-chaotic systems that exhibit long-range interactions, memory effects and multi-fractality. The analysis and results demonstrate that the seismic coda waves increments deviate from the Gaussian shape and their respective pdfs could adequately be described and processed by the q-Gaussian distribution. Furthermore and in order to investigate the dynamical structure of the volcanic-tectonic activity, we estimate the q-indices derived from the pdfs of the coda wave time series increments during the period 2009 - 2014 and present their variations as a function of time and as a function of the local magnitude (ML) of the events prior, during and after the caldera unrest.

 

 Acknowledgments. We acknowledge support by the project “HELPOS – Hellenic System for Lithosphere Monitoring” (MIS 5002697) which is implemented under the Action “Reinforcement of the Research and Innovation Infrastructure”, funded by the Operational Programme "Competitiveness, Entrepreneurship and Innovation" (NSRF 2014-2020) and co-financed by Greece & European Union (ERDF)
A new method to measure amino sugar isomers and amino acids in soil extracts and soil hydrolysates based on AccQ.Tag-chemistry and reversed phase ultra-high-performance liquid chromatography
Authors: Salas Erika , König Alexander , Kaiser Christina , Wanek Wolfgang
Published: March 2020

Soil microbial necromass represents a significant proportion (>50%) of soil organic matter (SOM). Microbial necromass consists mainly of particulate organic residues from fragmented cells walls and other slow turnover cytoplasmic components of dead fungi and bacteria. Some of the key components of microbial cell walls, such as peptides and amino sugar polymers, can remain and accumulate in the soil over prolonged times. Amino sugars have been used as biomarkers to quantify the contribution of microbial necromass to stabilized SOM. The different amino sugars present in polymeric form in soils can be released by acid hydrolysis and allow the estimation of the contribution of both fungal and bacterial necromass to the SOM pool. Among the amino sugars, hexosamine isomers (glucosamine, galactosamine, mannosamine) and muramic acid (the ether of lactic acid and glucosamine) are the most abundant ones. Muramic acid is specific to bacterial peptidoglycan while glucosamine is an abundant cell wall component of both, fungal chitin and bacterial peptidoglycan.

There are several chromatographic methods to measure free and bound amino sugars and amino acids in soil extracts and soil hydrolysates, but none of them allow the combined determination of amino sugar biomarkers and amino acids simultaneously in a single assay for rapid analysis. This is important as a large fraction of soil necromass N (>50%) consists of non-amino sugar-N, such as proteins and nucleic acids. In this study we therefore adopt a method based on 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AccQ.Tag) derivatization of amino compounds and optimized chromatographic (reversed phase) separation to simultaneously measure amino sugars (isomers) and amino acids in soil extracts and soil hydrolysates using ultra-high-performance liquid chromatography coupled to fluorescence or UV detection.

The use of this method allows for fast, robust and highly sensitive quantification of amino acids and amino sugars in environmental samples at sub-micromolar levels. This approach will help to improve our understanding of soil microbial necromass dynamics and their inherent effect on soil C and N sequestration. The AccQ.Tag chemistry also allows compound detection by electrospray ionization (ESI)-mass spectrometry, enabling isotope (13C, 15N) tracing applications.
Warm Climate States during Last Glacial Cycle with a Multi-Resolution Climate/Ice Sheet Model
Authors: Gierz Paul , Ackermann Lars , Rodehacke Christian , Krebs-Kanzow Uta , Stepanek Christian , Barbi Dirk , Lohmann Gerrit
Published: March 2020

Interglacials during the Quaternary represent the youngest climate states in the paleoclimate record that are similar to potential warmer-than-present states during the Anthropocene. In particular, those periods with warmer reconstructed temperatures and/or higher sea levels provide insights into the mechanisms that may be at work now and in the future. To date, climate model simulations of Quaternary Interglacials have been restricted to Atmosphere-Biosphere-Ocean simulations, with static ice sheet geometries from glaciological, geological, and geophysical reconstructions. Simulations including fully interactive ice sheets have not been widely available. Here, we present the first simulations of the PMIP4 timeslices for the Holocene and the Last Interglacial (LIG) with a fully coupled multi-resolution climate/cryosphere model, the AWI-ESM. We compare the simulated snapshots for the Holocene and LIG to simulations to proxy reconstructions, and to runs without dynamic ice sheets to highlight the processes now represented by the improved model. Furthermore, we show various schemes implemented in our model system to represent the ice sheet mass balance, both from surface ablation as well as ocean interaction. We find that both the Holocene and Last Interglacial ice sheets contain a smaller volume of ice compared to present day, with relative sea level equivalent changes of -3% and -7%, respectively.
Cassini state of Galilean Moons: Influence of a subsurface ocean
Authors: Coyette Alexis , Baland Rose-Marie , Lemaitre Anne , Van Hoolst Tim
Published: March 2020

Large moons such as the Galilean satellites are thought to be in an equilibrium rotation state, called a Cassini state (Peale, 1969). This state is characterized by a synchronous rotation and a precession rate of the rotation axis that is equal to the precession rate of the normal to its orbit. It also implies that the spin axis, the normal to the orbit and the normal to the Laplace plane are coplanar with a (nearly) constant obliquity.

For rigid bodies, up to 4 possible Cassini states exist, but not all of them are stable. It is generally assumed that the Galilean satellites are in Cassini State I for which the obliquity is close to zero (see e.g. Baland et al. 2012). However, it is also theoretically possible that these satellites occupy or occupied another Cassini state.

We here investigate how the interior structure, and in particular the presence of a subsurface ocean, influences the existence and stability of the different possible Cassini states.

References :

Baland, R.M., Yseboodt, M. and Van Hoolst, T. (2012). Obliquity of the Galilean satellites: The influence of a global internal liquid layer. Icarus 220, 435-448.

Peale, S. (1969). Generalized Cassini’s laws. Astron. J. 74 (3), 483-489.
Upscaling runoff and evapotranspiration fluxes in the Little Washita watershed using physically-based hillslope models
Authors: Picourlat Fanny , Mouche Emmanuel , Mugler Claude
Published: March 2020

Several authors in the literature, such as Khan (2014) and Loritz (2017), have previously suggested that 3D catchment hydrology can be predicted from 2D hillslope simulations. Following this idea, we propose an upscaling methodology for runoff and evapotranspiration fluxes. The first step consists of a geomorphic analysis of the studied watershed. The average mean slope and hillslope length are then used to build a 2D equivalent-hillslope model. The validity of the methodology is tested by comparing the resulting water balance with a 3D physically-based distributed model. 2D fluxes of the equivalent hillslope are converted into 3D by using the drainage density. This upscaling methodology is applied to the Little Washita (LW) watershed (Oklahoma, USA). Both the 3D reference model and the 2D equivalent model are built with the physically-based distributed code HydroGeoSphere, which is forced by LW reanalysis climatic data. Two decades are simulated. Regarding the evapotranspiration, the upscaling methodology with only one equivalent hillslope gives a good prediction of 3D fluxes. However, a combination of several hillslopes is needed for simulating the 3D flow rate at the basin’s outlet. This work on the decrease of model dimensionality is a first step in the upscaling process from 3D physically-based models to 1D column models used in global Land Surface Models.
Measurement of NOx and Ozone over the North Atlantic Ocean.
Authors: Lee James , Squires Freya , Andersen Simone , Hopkins Jim , Pasternak Dominika , Archibald Alex
Published: March 2020

Tropospheric ozone (O3) can adversely affect human health and environmental ecosystems and it is therefore vitally important to understand its formation pathways from both natural and anthropogenic precursors. Background O3 levels in the Northern Hemisphere have increased by more than a factor of two over the last century and it is believed that this increase is strongly tied to the increase in and distribution of anthropogenic nitrogen oxide (N0x) emissions. This is important as the changing level of O3 in the background troposphere impacts the ability of countries downwind to achieve their air quality standards.

As part of the NERC funded North Atlantic Climate System Integrated Study (ACSiS) and Methane Observations and Yearly Assessments (MOYA) projects, multiple research flights have taken place over the North Atlantic Ocean, spanning an area from 55oN to 12oN and 8oW to 25oW using the UK’s large research aircraft (The Facility for Airborne Atmospheric Measurements – FAAM). Flights took place in all seasons from 2017 – 2020. A variety of gas and aerosol measurements were made, including NOx, O3, CO and a range of VOCs and an overview of the data is presented here. Measurements were taken in a range of air masses, including biomass burning outflow from West Africa, urban outflow from Europe and emissions from the busy shipping lanes to the West of Portugal.

Data was analysed to assess O3 formation from the different emission sources, in particular examining the difference between anthropogenic and natural emissions. In addition, the output of regional chemistry models is compared to the data in order to assess the performance of the models in predicting O3 and its precursors.
Spatial and temporal changes of sediment grain size along Israel’s Mediterranean cliff-dominated beaches
Authors: Crouvi Onn , Shemesh Ran , Katz Oded , Mushkin Amit , Morag Navot , Lensky Nadav
Published: March 2020

Beach morphodynamics are largely controlled by the interaction of wave climate with beach sediments. Local changes in sediment grain size, shape or density can lead to distinct morphological changes of beach systems subjected to similar energetic inputs. Whereas the spatial variation of grain size along beach profiles has been well studied, the temporal variation in beach grain size has received less attention. Moreover, the fate of cliff-eroded sediments along sandy coasts, with limited tidal effect, was rarely studied as most studies focused on shingle beaches (rocky/pebble rich) especially in coastal environments where tide plays an important role.

Here we use grain size data to explore the temporal dynamics of beach sediments in cliff-dominated beaches along Israel’s Mediterranean coast and their relationship to cliff erosion as well as sand abrasion/attrition. Our approach is based on repetitive seasonal-scale sampling of surficial sediments along cross shore transects over 3 years. We found that most samples exhibit unimodal particle size distribution (PSD), with a mode either at the fine sand fraction (180-220 µm) composed of quartz, or at the coarse sand to very coarse sand fraction (900-1,200 µm), composed of eolianite rock chips. The coarse fraction dominants the PSD mostly during winter times, whereas at summer times it is usually absent. In addition, this coarse fraction decreases with time that passed since waves reached the cliff base during sea storms. Our results suggest that: 1) The addition of the coarse fraction during winter is related to high-energy wave storms that mobilize and transport cliff-derived materials (taluses) along the beach, and 2) The disappearance of the coarse fraction towards summer is related to sand abrasion by wave and/or by wind action, i.e. breakage of the ~1 mm eolianite rock chips into ~200 µm quartz grains. Our findings emphasize the importance of cliff erosion and sand abrasion in controlling the temporal variation in PSD along cliff-dominated beaches.
Detection of Magnetic Signals from Ocean Circulation with Satellite Altimetry and Magnetometer
Authors: Hornschild Aaron , Saynisch-Wagner Jan , Irrgang Christopher , Petereit Johannes , Thomas Maik
Published: March 2020

Electrically conducting sea-water moves through Earth's magnetic field and generates electromagnetic signals itself. These signals can be detected by space borne Earth observation technologies, like the Swarm satellite magnetometer mission. In contrast to already successfully detected ocean tidal magnetic signatures, the magnetic signals from ocean circulation are still unidentified in observations. However, the electromagnetic signals from the ocean circulation would be an additional, interesting source of information.
We propose, that satellite altimetry can be helpful in order to detect magnetic signals from ocean circulation. Sea surface height measurements allow to estimate depth-integrated current velocities by using the geostrophic approximation, which describes a balance between sea surface height gradients and horizontal currents. With the resulting integrated electric current density, the magnetic signals from ocean circulation can be calculated using an electromagnetic induction solver. In a further step, the estimations are a basis for the  separation of magnetometer observations and for data assimilation.
Therefore, it is necessary that the geostrophic approach reflects the realistic time behavior of electromagnetic signals from ocean circulation. Ocean model data allows to verify this approach with respect to the identification of magnetic signals from ocean circulation in satellite magnetometer observations. We present this analysis and report about the feasibility of this approach regarding the Swarm mission and possible future missions.
Spatial distribution of (137)Cs in reference soil sites of South America to reconstruct soil erosion in intensive agricultural landscapes during the Anthropocene
Authors: Chaboche Pierre-Alexis , Evrard Olivier , Lefèvre Irène
Published: March 2020

Land degradation and fine sediment supply induced by soil erosion processes are exacerbated in intensively cultivated catchments of South America, leading to deleterious consequences for ecosystems and to the disturbance of global biogeochemical cycles. In order to evaluate the sustainability of agricultural practices, a fundamental prerequisite is to quantify soil erosion rates and compare them with the tolerable soil losses. Although its use has been debated in the literature, the fallout radionuclide (137Cs) is one of the few techniques available to reconstruct soil redistribution rates during the Great Acceleration period. Accordingly, it is increasingly used to quantify soil redistribution rates in catchments across the world. Assessment of erosion and deposition rates is commonly based on the comparison of (137Cs) inventories in undisturbed soil profiles (i.e. where neither erosion nor deposition has occurred) and those measured at locations affected by soil redistribution in the landscape. However, in intensive agricultural landscapes, appropriate reference sites can be difficult to find. The objective of this study is to determine and map the initial (137Cs) fallout at the scale of South America, based on measurements made on reference soil sites and spatialized co-variables. This new map will be useful for the scientific community and public authorities to evaluate the sustainability of farming practices, especially in the eastern part of South America where intensive agricultural practices dominate. Furthermore, the methodology presented here could be applied to other regions located in the Southern Hemisphere in order to avoid the systematic sampling of reference sites for conducting soil erosion studies using the (137Cs) technique.
Lessons learnt from quality-checking observed and simulated river flow data worldwide
Authors: Arheimer Berit , Crochemore Louise , Pineda Rafael , Isberg Kristina , Pineda Luis , Hasan Abdulghani , Andersson Jafet
Published: March 2020

Advances in open data science serve large-scale model developments and, subsequently, hydroclimate services. Local river flow observations are key in hydrology but data sharing remains limited due to unclear quality, or to political, economic or infrastructure reasons. This presentation provides methods for quality checking openly accessible river-flow time series. Availability, outliers, homogeneity and trends were assessed in 21 586 time series from 13 data providers worldwide. We found a decrease in data availability since the 1980s, scarce open information in southern Asia, the Middle East and North and Central Africa, and significant river-flow trends in Africa, Australia, southwest Europe and Southeast Asia. We distinguish numerical outliers from high-flow peaks, and integrate all investigated quality characteristics in a composite indicator.

Some 5338 gauges from these river flow time series (> 10 years) were used in the evaluation of the Worldwide-HYPE (WWH) hydrological model at the global scale (half for calibration and half for independent validation), resulting in a median monthly KGE of 0.4. However, WWH performance varies widely spatially and with the target flow signature. The model performs best (KGE > 0.6) in Eastern USA, Europe, South-East Asia, and Japan, as well as in parts of Russia, Canada, and South America. It also shows overall good potential to capture flow signatures of monthly high flows, spatial variability of high flows, duration of low flows, and constancy of daily flow. Nevertheless, there remains large potential for model improvements and we suggest both redoing the parameter estimation and reconsidering parts of the model structure for the next WWH version.

References:

Crochemore, L., Isberg, K., Pimentel, R., Pineda, L., Hasan, A., Arheimer, B., (2019). Lessons learnt from checking the quality of openly accessible river flow data worldwide. Hydrological Sciences Journal. https://doi.org/10.1080/02626667.2019.1659509

Arheimer, B., Pimentel, R., Isberg, K., Crochemore, L., Andersson, J. C. M., Hasan, A., Pineda, L., (accepted). Global catchment modelling using World-Wide HYPE (WWH), open data and stepwise parameter estimation. Hydrology and Earth System Sciences Discussions. In press. https://doi.org/10.5194/hess-2019-111
Evaluating the Potential of Satellite Measurements in Air Quality Monitoring: A Project for the Finnish Ministry of the Environment
Authors: Virta Henrik , Sundström Anu-Maija , Ialongo Iolanda , Tamminen Johanna
Published: March 2020

We present the results of a project for the Finnish Ministry of the Environment that aimed to assess the potential of satellite measurements in complementing traditional in situ air quality measurements. Co-located NO2 measurements from the TROPOspheric Monitoring Instrument (TROPOMI) and several traditional air quality stations (measuring in µg/m3) in Finland and Europe between April 2018 and June 2019 are compared to determine their correlation. We find that the correlation of individual air quality stations with TROPOMI is dependent on the location of the station, but is more reliable when all stations in a city centre are studied as a group. This is expected due to the spatial averaging of satellite measurements. We also find that NO2 measurements between different cities in Finland and Europe in general correlate well.

We also analyse TROPOMI’s and the Ozone Monitoring Instrument’s (OMI) ability to study the spatial distribution of NO2 over Finland and the Helsinki metropolitan area using gridded maps. Oversampled TROPOMI measurements are able to distinguish relatively small sources such as roads and airports, and the difference in concentrations between weekdays and weekends. TROPOMI is also able to detect emissions from different sources of NO2 such as cities, mining sites and industrial areas. Long time series measurements from OMI show decreasing NO2 levels over Finland between 2005 and 2018.

Finally, we convert air quality station measurements to vertical column densities using boundary layer height data, and study the effect that this has on their correlation with TROPOMI measurements.

This study was conducted on behalf of the Finnish Ministry of the Environment, and showcases how satellite measurements can be used reliably alongside traditional air quality measurements to provide a better picture of current pollution levels. Launched in 2017, TROPOMI is currently the highest-resolution air quality sensing satellite, and its societal uses are only beginning to be realized. Future Sentinel missions, especially the geosynchronous Sentinel-4, will provide an even more comprehensive view of the daily air quality situation.
Degradation of permafrost carbon in the Kolyma River
Authors: Keskitalo Kirsi , Bröder Lisa , Jong Dirk , Zimov Nikita , Davydova Anya , Davydov Sergey , Tesi Tommaso , Mann Paul , Haghipour Negar , Eglinton Timothy , Vonk Jorien
Published: March 2020

Soil temperatures in permafrost (i.e. perennially frozen ground) are rising globally. The increasing temperatures accelerate permafrost thaw and release of organic carbon, that has been locked in permafrost soils since the last glacial period, to the contemporary carbon cycle. The potential remineralisation of organic carbon to greenhouse gases can contribute to further climate warming. Particulate organic carbon (POC) in the Kolyma River is older than dissolved organic carbon (DOC) thus serves as a good tracer for abrupt permafrost thaw (i.e. river bank erosion and thermokarst) that dominantly releases old POC. While dissolved organic carbon (DOC) mobilised from the old Yedoma outcrops on the banks of the Kolyma River is shown to be highly labile, vulnerability of POC to biodegradation is not yet known. In this study we aim to constrain degradation rates for POC in the Kolyma River. To capture seasonal variability of the POC pool and its degradation rate the incubation was conducted both during the spring freshet and in late summer (2019 and 2018, respectively). We incubated whole-water samples over 9 to 15 days and quantified POC (and DOC) loss over time, as well as dissolved inorganic carbon (DIC). The incubation was carried out in the dark. We also tracked changes in POC composition and age with carbon isotopes (d13C-OC, d13C-DIC, ∆14C). Preliminary results from 2018 suggest a decrease in POC concentrations of up to 30 % while those of DOC decrease by up to 11 %. The rate of POC degradation is nearly three times faster than DOC though the absolute amounts of DOC are in turn higher than those of POC (< 1 mg L-1 for POC and ~3 mg L-1 for DOC). Furthermore, the changes in d13C of POC, DOC and DIC suggest ongoing microbial degradation and conversion of organic carbon into inorganic carbon. These first estimates show that POC degrades fairly rapidly while transported in the Kolyma River. A better understanding of POC degradation along lateral flow paths is critical for improving our knowledge of permafrost thaw and its possible climate impacts in the future.
Monitoring submerged riverine macroplastics using echo sounding
Authors: Broere Sophie , van Emmerik Tim , González-Fernández Daniel , Luxemburg Willem , Cózar Andrés , van de Giesen Nick , de Schipper Matthieu
Published: March 2020

Riverine plastics cause severe global problems, regarding the risk for human health and environmental damage. The major part of the plastic waste that ends up in the oceans is transported via rivers. However, estimations of global quantities of plastics entering the oceans are associated with great uncertainties due to methodological difficulties to accurately quantify land-based plastic fluxes into the ocean. Yet, there are no standard methods to determine quantities of plastics in rivers. For the sake of reducing the amount of plastic waste in the natural environment, information on plastic fluxes from rivers to seas is needed. Focussing on monitoring of the plastic litter that is transported by rivers is useful because measures can easier be implemented in rivers than in seas. Moreover, consistent measuring techniques are crucial to optimise prevention-and mitigation strategies, especially in countries with high expected river plastic emissions.

Additionally, based on plastic characteristics and turbulent river flow conditions, a considerable portion of the riverine litter can also be transported underneath the surface in the water column. Current monitoring methods regarding macro plastics are labour intensive and do not provide continuous measurements for submerged riverine plastics. Besides, most research done focussed on floating macro litter, instead of submerged plastics. The aim of this research was to find a standard method, applicable in different river systems, for detecting submerged macro plastics.

With the use of the Deeper Chirp+ fishfinder, several tests were conducted both in the Guadalete river basin in southern Spain and in the lab at the TU Delft. Spanish, and in general European rivers are estimated to transport two to three orders of magnitude below rivers in Asia (Malesia and Vietnam), and should not be neglected. The Guadalete river basin formed a suitable location to test this new method. First, monitoring in the Guadalquivir river was executed, with the use of a net to validate the readings of the sonar. Furthermore, the detecting abilities of the echosounder, in the Guadalete river basin, were tested with the use of plastic targets. The targets were released in the river and passed the sensor at a certain time. Moreover, tests in the lab at the TU Delft were conducted to investigate relations between sonar signal and flow velocity, object depth, and object size.

The tests show that submerged macro plastics can be detected with the use of echo sounding. Moreover, a relation between the sonar signal and litter size is found. Finally, signal intensities can be related to object properties. In conclusion, the use of echo sounding has a high potential for obtaining more accurate plastic flux estimations.
Fusion of Sentinel and PlanetScope images for high resolution soil moisture mapping: Algorithm and preliminary validation
Authors: Gašparović Mateo , Kumar Singh Sudhir
Published: March 2020

High resolution remote sensing images plays a critical role in detection and monitoring of land degradation and development. Monitoring the soil parameters represents great importance for sustainable development and agriculture, as well as smart food production. The space segment component of the Copernicus programme (e.g., Sentinel-1, Sentinel-2 etc.) enables continuously monitoring of Earth’s surface at 10-m spatial resolution. New technologies, development, and minimization of sensors led to the development of micro-satellites (e.g., PlanetScope). These satellites allow us to monitor the Earth's surface daily in 3-m spatial resolution. The developed algorithm for soil moisture mapping is based on the fusion of Sentinel-2 and PlanetScope images. This allows a soil moisture mapping in high spatial resolution. Soil moisture was estimated based on the Leaf Area Index (LAI) and Enhanced Vegetation Index (EVI) using modified water cloud model. Ground-truth data were collected from 15 stations of the International Soil Moisture Network across the globe and used for mapping and validation of soil moisture. The developed algorithm provides a new knowledge that can be widely applied in various research for the detection and monitoring of land degradation and development.
Aerosol - Climate Interactions, the Distribution of Aerosol Impacts, and Implications for the Social Cost of Carbon
Authors: Burney Jennifer , Persad Geeta , Proctor Jonathan , Burke Marshall , Bendavid Eran , Heft-Neal Sam , Caldeira Ken
Published: March 2020

Here we demonstrate how the same aerosol emissions, released from different locations, lead to different regional and global changes in the physical environment, in turn resulting in divergent magnitudes and spatial distributions of societal impacts. Atmospheric chemistry and the general circulation do not evenly distribute aerosols around the globe, so aerosol impacts -- both direct and via interactions with the general circulation -- vary spatially. Our repeat-cycle perturbation experiment shows that the same emissions, when released from one of 8 different regions, result in significantly different steady-state distributions of surface particulate matter (PM2.5), total column aerosol optical depth (AOD), surface temperature, and precipitation. We link these changes in the physical environment to established temperature, precipitation, AOD, and PM2.5 damage functions to estimate both local and global impacts on infant mortality, crop yields, and economic growth. Because the damages associated with these aerosol and aerosol precursor emissions are strongly emission-location dependent, the marginal dollar spent on mitigation would have very different returns in different locations, both locally and globally. This has important implications for calculating a realistic social cost of carbon, since these aerosol-mediated effects are ultimately inseparable from the processes producing CO2 emissions.
ENSO amplitude uncertainty under global warming in CMIP5 models
Authors: Beobide Goratz , Bayr Tobias , Reintges Annika , Latif Mojib
Published: March 2020

The possible change of ENSO amplitude during the 21st century in response to global warming has been analyzed in models participating in the Coupled Model Intercomparison Phase 5 (CMIP5). Three types of uncertainties are investigated: scenario uncertainty, model uncertainty, and uncertainty due to internal variability.

The ENSO response obtained from the CMIP5 models is highly uncertain, leading to an ensemble-mean amplitude change of close to zero until the end of the 21st century, with an uncertainty exceeding 0.3 °C. The internal variability is the main contributor to the uncertainty during the first two decades of the projections. The inter-model differences dominate thereafter, while scenario uncertainty is relatively small throughout the whole 21st century. The zonal wind-SST feedback has been identified as an important factor of ENSO amplitude change: the global warming signal in the ENSO amplitude and zonal wind-SST feedback are highly correlated across the CMIP5 models, with correlation coefficients of 0.87, 0.84 and 0.78 for the RCP4.5, RCP6.0 and RCP8.5 scenarios, respectively.

The CMIP5 models with realistic ENSO dynamics have been analyzed separately. In this sub-ensemble, the global warming signal is strengthened with a mean ENSO amplitude decrease of approximately 0.1°C by the end of the 21st century. When only considering models with large decadal ENSO amplitude variability, the decrease in ENSO amplitude amounts to 0.1°C and 0.2°C for the RCP4.5 and RCP8.5 scenarios, respectively.
Snow Data Assimilation Methods for Hydrological, Land Surface, Meteorological and Climate Models: Results from COST HarmoSnow (2014-2018)
Authors: Helmert Jürgen , Şensoy Şorman Aynur , Alvarado Montero Rodolfo , De Michele Carlo , De Rosnay Patricia , Dumont Marie , Pullen Samantha , Finger David Christian , Lange Martin , Picard Ghislain , Potopová Vera , Vikhamar-Schuler Dagrun , Arslan Ali Nadir
Published: March 2020

Snow as a major part of the cryosphere is an important component of Earth’s hydrological cycle and energy balance. Understanding the microstructural, macrophysical, thermal and optical properties of the snowpack is essential for integration into numerical models and there is a great need for accurate snow data at different spatial and temporal resolutions to address the challenges of changing snow conditions.

Physical snow properties are currently determined by traditional ground-based measurements as well as remote sensing, over a range of temporal and spatial scales, following considerable developments in instrument technology over recent years. 

Data assimilation (DA) methods are widely used to combine data from different observations with numerical model using uncertainties of observed and modeled variables  to produce an optimal estimate. DA provides a reliable improvement of the initial states of the numerical model and a benefit for hydrological and snow model forecasts.

 

European efforts to harmonize approaches for validation, and methodologies of snow measurement practices, instrumentation, algorithms and data assimilation techniques were coordinated by the European Cooperation in Science and Technology (COST) Action ES1404 “HarmoSnow”, entitled, “A European network for a harmonized monitoring of snow for the benefit of climate change scenarios, hydrology and numerical weather prediction” (2014-2018) .

One of the key objectives of the action was “Advance the application of snow DA in numerical weather prediction (NWP) and hydrological models, and show its benefit for weather and hydrological forecasting as well as other applications.” 

One key result from COST HarmoSnow is a better knowledge about the diversity of usage of snow observations in DA, forcing, monitoring, validation, or verification within NWP, hydrology, snow and climate models. The main parts of this knowledge are retrieved from a COST HarmoSnow survey exploring the common practices on the use of snow observations in different modeling environments. We will show results from the survey and their implications towards standardized and improved usage of snow observations in various data assimilation applications.