bluuebunny/crossref_metadata_2025 huggingface dataset:
Validation of Sentinel-5p retrieved cloud height data using ground-based radar/lidar measurements from the CLOUDNET network
Authors: Compernolle Steven , Argyrouli Athina , Lutz Ronny , Sneep Maarten , Granville José , Hubert Daan , Keppens Arno , Verhoelst Tijl , Fjaeraa Ann Mari , Loyola Diego , O'Connor Ewan , Lambert Jean-Christopher
Published: March 2020

Satellite measurements of tropospheric or total column trace gas species, including those from Sentinel-5p TROPOMI, are affected by the presence of clouds. Therefore, cloud data products retrieved with the same sensor play an essential role, as they allow the data provider to take an estimated cloud impact on the trace gas retrieval into account. Examples are the modification of the radiative transfer and associated quantities such as the air mass factor, and the partial masking of the measurement scene. Evidently, the accuracy of these corrections relies on the accuracy of the retrieved cloud properties, like radiometric cloud fraction (CF), cloud top height (CTH) or cloud height (CH), and cloud optical thickness (COT) or cloud albedo (CA).

We consider here three S5p TROPOMI-based cloud products: (i) L2_CLOUD OCRA/ROCINN CAL (Optical Cloud Recognition Algorithm/Retrieval of Cloud Information using Neural Networks; Clouds-As-Layers), (ii) L2_CLOUD OCRA/ROCINN CRB (Clouds-as Reflecting Boundaries), and (iii) the S5p support product FRESCO-S (Fast Retrieval Scheme for Clouds from Oxygen absorption bands). These are input to the S5p operational processors for several trace gas products, including ozone columns and profile, total and tropospheric NO2, formaldehyde, sulfur dioxide. The quality assessment of these cloud products is carried out within the framework of ESA’s Sentinel-5p Mission Performance Centre (MPC) with support from AO validation projects focusing on the respective trace gases.

In this work, cloud height (from S5p CLOUD CRB and S5p FRESCO algorithms) and cloud top height (from S5p CLOUD CAL) S5p data is validated with radar/lidar-based cloud profile information from the ground-based networks CLOUDNET and ARM at 17 sites. For some sites the comparison is difficult due to e.g., orography or snow/ice cover. S5P and CLOUDNET report similar cloud height variations at several sites, and the correlation between the S5p cloud products and CLOUDNET can be high (Pearson R up to 0.9). However, there is a site-dependent negative bias of the S5p cloud (top) height with respect to the CLOUDNET data: up to -2.5 km for S5p CLOUD CAL cloud top height and -1.5 km for S5p CLOUD CRB and S5p FRESCO cloud height. The dependence on other parameters measured by S5p and CLOUDNET (e.g., radiometric cloud fraction, cloud phase,…) is investigated.
Memory of Arctic sea ice in model simulations, observations, and reanalyses
Authors: Gieße Céline , Notz Dirk , Baehr Johanna
Published: March 2020

The strong decline of Arctic sea ice in recent years has raised growing interest in seasonal-to-interannual predictions of Arctic sea ice. Previous studies have revealed a large predictability gap between potential and operational forecast skill of Arctic sea ice, which could indicate a strong potential for improvement of operational sea ice predictions or hint at a systematic overestimation of sea ice memory in current climate models.

Here, we assess and compare memory of Arctic sea ice in terms of lagged correlations of sea ice area anomalies on seasonal to interannual time scales in a large model ensemble (MPI Grand Ensemble) as well as several reanalysis and observational products. While the different datasets show good agreement for short-term memory on time scales of a few months on which persistence is the dominant source of memory, we find substantial differences between model and observational memory behaviour on longer time scales. In particular, we find that memory from the summer sea ice minimum into the following year is significantly overestimated in the model, as lagged correlation values in all observational datasets are outside the range of model variability. Reanalysis data show correlation values that lie in between observational and model mean values, underpinning the hybrid nature of reanalyses combining observations and model behaviour. Extending the analysis of sea ice memory to a regional scale provides further information on the spatial origin of specific memory features in the different datasets and helps in understanding differences between model and real-world behaviour on a physical process level.
In situ determination of water-saturated solidus by electrical discontinuity
Authors: Guo Xuan , Ni Huaiwei
Published: March 2020

Water plays an important role in lowering melting temperature of rocks. The water-saturated solidus of rock is critical for understanding the magma generation and the dynamics of the Earth. There have been a lot of water-saturated solidi of rocks constrained by traditional quench method in literature. However, since both of the hydrous silicate melt and aqueous fluid can be quenched to glasses at high pressure, it is difficult to discriminate whether the quenched glasses were from melt or not. As a result, the water-saturated solidi of rocks from different studies may show significant discrepancy. One way to solve this problem is to detect the characteristics change of the rock system in situ, and electrical conductivity measurement is one of the good options. It is known that hydrous melt has much higher electrical conductivity than solid rock, and temperature is much more effective in enhancing melt electrical conductivity than that for aqueous fluid. Once the partial melting is triggered, the electrical conductivity of the water-saturated rock system may have remarkable increase if the hydrous melt is interconnected in the system. Accordingly, the abrupt change of electrical conductivity may mark the solidus temperature. In this study, we performed electrical conductivity measurement for the determination of water-saturated solidus of albite. We adopted albite as the starting material because its water-saturated solidus is well known, which can help to verify the accuracy our method, and its quenched products are not so controversial. The electrical conductivity measurements were carried out at four different pressures ranging from 0.35 GPa to 1.7 GPa in a 3/4″ piston cylinder apparatus with impedance spectroscopy. The obvious change of electrical conductivity was observed at solidus temperature within error, with increase of 1.8-0.18 log unit at 0.35-1.7 GPa. The results showed a stronger increase of conductivity at lower pressures, and fitted well with the water-saturated solidus of albite in literature. One defect of this method is the loss of water during experiment. The final water content in the system is about 1-2 wt%, comparing to the initial 10-15 wt% H2O. Nevertheless, the whole system is still water saturated, since water solubility in albite is fairly low. Therefore, if such a method can be improved to keep more water, it may be applied to other rocks to better constrain the water-saturated solidi in the future.

 
Using the Jupyter Notebook as a Tool for analyzing the EUMETSAT HSAF snow products
Authors: Akyurek Zuhal , Bolat Kenan , Karaman Cagri Hasan , Takala Matias
Published: March 2020

Snow cover is an essential climate variable directly affecting the Earth’s energy balance, therefore estimating the snow parameters play an important role in hydrological, land surface, meteorological and climate models. Remote sensing provides a good understanding of snow cover monitoring thus several satellite snow products have been developed and disseminated so far.  In this study, Jupyter Notebook as an open source interactive satellite snow products retrieval, visualization and analysis tool has been developed by using Python language. Jupyter Notebook allows easy and straightforward data analysis with the possibility of live interaction and requires little programming knowledge.

The developed tool provides the capabilities of downloading the satellite snow products, georeferencing them and performing spatial analysis like zonal statistics. In this study EUMETSAT HSAF snow products, namely H10 (Snow detection), H13 (Snow Water Equivalent) and H34 (Snow cover) are used. The tool allows user to upload their own region in ESRI shapefile format for spatial and temporal analysis and the uploaded region can be visualized on interactive map via custom interactive widget like ipyleaflet. The cloud percentage for the snow cover product can be selected and daily snow covered area or snow water equivalent change for the uploaded region can be calculated for the selected period. With this tool, it is aimed to retrieve the satellite snow products easily and perform spatial and temporal analysis of snow cover for the area of interest without getting lost in data formats. Therefore, users with little or no knowledge about programming can interact easily with EUMETSAT HSAF snow products. Furthermore, with the high extensibility of Jupyter Notebook, it can also be improved or modified in accordance with the need of the end users.
Towards a resilient water future via inter-basin water transfer: climate impact assessment and feasibility study
Authors: Khadem Majed , Dawson Richard , Walsh Claire
Published: March 2020

Uneven distribution of water resources in the face of climate change and population growth is imposing increasing threats to communities as well as challenging decision-makers. Inter-basin water transfer (IBT) schemes have been appreciated as one of the common approaches to tackle this issue. This work presents a framework for climate impact assessment and feasibility study for IBTs. The framework investigates negative impacts of IBTs on the donor and receiving bodies. This is done by calculating hydrological drought risk and environmental risks to freshwater habitats under 1200 future climatic scenarios and two different transfer scenarios. 2.2 Km resolution time-series from UK’s Met Office most recent climate projection (UKCP18) is used as the input scenario and a water resources model developed at Newcastle University is implemented to determine allocation and calculate the above risk factors. This work considers transferring raw water from England’s water-rich North East to its water-stressed South East as the case study. This case was chosen because England, with no major IBT scheme, is experiencing challenges from more frequent climate change and increasing demand for water in London. Additionally, organisations such as National Infrastructure Commission (NIC) and Environment Agency (EA) have encouraged England’s water companies to consider IBT as one of the options to improve water supply resilience. In this study, we assess schemes to transfer water using the existing infrastructures of water companies located from North East to South East of England to minimise costs and environmental impacts. Results suggest that, under a wide range of future scenarios, meeting London’s annual water shortage through transfers from the North East during wet season of each year not only increases London’s water supply resilience but also boosts flood resilience in the North East donor basin while still meeting environmental requirements.
Measuring the electrical and optical properties of fog using balloon borne instrumentation in the UAE
Authors: Marlton Graeme , Harrison Giles , Nicoll Keri , Ambaum Maarten
Published: March 2020

Countries in arid and desert climates that have small amounts of rainfall each year use cloud seeding techniques to enhance the little rainfall that is present. Typically, this is achieved by seeding the cloud with hygroscopic nuclei to increase the rainfall. A possible alternative method is to inject the cloud with electric charge, which has been shown in models to alter the droplet size and distribution and influence rainfall properties.

Here, in-situ observations of the electrical and optical properties of clouds are described from a desert site. These are used to inform droplet growth models. For this, a yearlong campaign, during which 10 weather balloons carrying electric charge and optical sensors were launched through fog layers from Abu Dhabi airport, United Arab Emirates. Here we present 2 case studies. The first is a clear air ascent comparison between the desert site at Abu Dhabi and a temperate site in northern Finland. The second is a fog comparison between Abu Dhabi and a temperate site in the United Kingdom

The results show that the fogs in Abu Dhabi are highly charged with a charge density of 0.1-1 nC m-3 as opposed to the charge densities of fogs in Northern Hemisphere temperate regions which have a typical charge density of 10 pC m-3. The droplet concentration in the Abu Dhabi fog case study is significantly smaller, approximately 150 cm-3 as opposed to droplet concentrations of 300-400 cm-3 in fog over a temperate site.

The results suggest that dust contributes strongly to the atmospheric electrical conditions in the UAE region, due to charging of the dust tribo-electrically. This dust charge may also affect the droplet distribution within the fog. These new measurements of the vertical profile of charge through fog layers in desert climates will be used to improve understanding in droplet growth models.
Seismic mantle anisotropy associated with subduction polarity reversal: Insights from numerical models
Authors: Kruse Jan Philipp , Schmeling Harro , Link Frederik , Ruempker Georg
Published: March 2020

The deep dynamics of continental collision is one of the least understood plate tectonic processes. One interesting process that is believed to be a feature of continental collision is a flip in subduction polarity. A prominent location where such a flip is proposed by different seismic tomography studies (e.g Kissling et al., 2006) are the eastern alps.

The aim of our study is to find a particular signature in the seismic anisotropy of the upper mantle that is the result of a temporal subduction polarity reversal. In our case the seismic anisotropy is produced by the LPO of mantle minerals due non-Newtonian deformation rates.

We use the thermo-mechanical 2D finite-difference code FDCON which has been extended to include a free surface with an erosion/sedimentation mechanism. For the geometrical setup an oceanic plate is placed between two continental plates. Subduction of the oceanic plate beneath the right continent is prescribed. The overriding plate (right) is pushed by constant kinematic boundary conditions. Among other parameters we varied a) the plastic strength of sediments (very weak to strong), b) the ductile rheology of the lower crust (felsic or mafic) and c) the convergence velocity of the two continents (1 - 10 cm/yr). From our results we can identify at least two different mechanisms for a subduction polarity switch.

To estimate the full elastic tensor at the grid points of interest, we use a modified version of DREX (Kaminski et al., 2004) that can handle a time dependent flow field. Using the full elastic tensors, we can calculate, e.g with MSAT (Walker & Wookey, 2012), effective delay times and fast shear wave polarization directions for arbitrary azimuths.

Our first results show significant differences between models with and without a subduction polarity reversal.
The relationship between extreme weather and low crop yields
Authors: Heino Matias , Anderson Weston , Puma Michael , Kummu Matti
Published: March 2020

It is well known that climate extremes and variability have strong implications for crop productivity. Previous research has estimated that annual weather conditions explain a third of global crop yield variability, with explanatory power above 50% in several important crop producing regions. Further, compared to average conditions, extreme events contribute a major fraction of weather induced crop yield variations. Here we aim to analyse how extreme weather events are related to the likelihood of very low crop yields at the global scale. We investigate not only the impacts of heat and drought on crop yields but also excess soil moisture and abnormally cool temperatures, as these extremes can be detrimental to crops as well. In this study, we combine reanalysis weather data with national and sub-national crop production statistics and assess relationships using statistical copulas methods, which are especially suitable for analysing extremes. Further, because irrigation can decrease crop yield variability, we assess how the observed signals differ in irrigated and rainfed cropping systems. We also analyse whether the strength of the observed statistical relationships could be explained by socio-economic factors, such as GDP, social stability, and poverty rates. Our preliminary results indicate that extreme heat and cold as well as soil moisture abundance and excess have a noticeable effect on crop yields in many areas around the globe, including several global bread baskets such as the United States and Australia. This study will increase understanding of extreme weather-related implications on global food production, which is relevant also in the context of climate change, as the frequency of extreme weather events is likely to increase in many regions worldwide.
Slow-down of the greening trend in natural vegetation with further rise in atmospheric CO2
Authors: Winkler Alexander J. , Myneni Ranga B. , Hannart Alexis , Brovkin Victor
Published: March 2020

Satellite data reveal widespread changes in vegetation cover of Earth’s land surfaces. Regions intensively attended to by humans are mostly greening due to land management. Natural vegetation, on the other hand, is exhibiting patterns of both greening and browning in all continents. Factors linked to anthropogenic carbon emissions, such as CO2 fertilization, climate change and consequent episodic disturbances (e.g. fires and droughts) are hypothesized to be key drivers of changes in natural vegetation. A rigorous regional attribution at biome-level that can be scaled into a global picture of what is behind the observed changes is currently lacking.

Therefore, we analyze here the longest available satellite record of global leaf area index (LAI, 1981-2017) and identify several clusters of significant long-term changes at the biome scale. Using process-based model simulations (fully-coupled MPI-M Earth system model and 13 stand-alone land surface models), we disentangle the effects of rising CO2 on LAI in a probabilistic setting applying Causal Counterfactual Theory.

Our analysis reveals a slowing down of greening and strengthening of browning trends, particularly in the last two decades (2000-2017). The decreases in LAI are primarily concentrated in regions of high LAI (i.e. tropical forests), whereas the increases are in low LAI regions (i.e. northern and arid lands). These opposing trends are reducing the LAI texture of natural vegetation at the global scale. The analysis prominently indicates the effects of climate change on many biomes – warming in northern ecosystems and rainfall anomalies in tropical biomes. Our results do not support previously published accounts of dominant global-scale effects of CO2 fertilization. Most models largely underestimate vegetation browning, especially in the tropical rainforests. The leaf area loss in these productive ecosystems could be an early indicator of a slow-down in the terrestrial carbon sink. Models need to better account for this effect to realize plausible Earth system projections of the 21st century.
SKS splitting observations across the Iranian plateau and Zagros: the role of lithosphere deformation and mantle flow
Authors: Kaviani Ayoub , Mahmoodabadi Meysam , Rümpker Georg , Yamini-Fard Farzam , Tatar Mohammad , Moradi Ali , Nilfouroushan Faramarz
Published: March 2020

We used more than one decade of core-refracted teleseismic shear (SKS) waveforms recorded at more than 160 broadband seismic stations across the Iranian plateau and Zagros to investigate seismic anisotropy beneath the region. Splitting analysis of SKS waveforms provides two main parameters, i.e., fast polarization direction and split delay time, which serve as proxies for the trend and strength of seismic anisotropy beneath the stations. Our observation revealed a complex pattern of splitting parameters with variations in the trend and strength of anisotropy across the tectonic boundaries. We also verified the presence of multiple layers of anisotropy in conjunction with the lithosphere deformation and mantle flow field. Our observation and modeling imply that a combined system of lithosphere deformation and asthenospheric flow is likely responsible for the observed pattern of anisotropy across the Iranian Plateau and Zagros. The rotational pattern of the fast polarization directions observed locally in Central Zagros may indicate the diversion of mantle flow around a continental keel beneath the Zagros. The correlation between the variation in lithosphere thickness and the trend of anisotropy in the study area implies that the topography of the base of lithosphere is also a determining factor for the pattern of mantle flow inferred from the observations.
The Copernicus Marine Environment Monitoring Service as a platform to map marine ecosystem services: a Lithuanian case study
Authors: Inácio Miguel , Kalinauskas Marius , Miksa Katarzyna , Gomes Eduardo , Pereira Paulo
Published: March 2020

Oceans and seas have always played an important role in supporting human wellbeing through the deliverance marine ecosystem services (MES). Nevertheless, the anthropogenic driven environmental degradation coupled with changes in socio-economic dynamics affected the capacity to deliver MES in quantity and quality. While it is of the utmost importance and need to map and assess MES, data deficiencies, data standardization, lack of knowledge on the functioning of multiple MES and poor spatial and temporal coverage, hinder its operationalization. The objective of this work was to test the applicability of databases and platforms like the Copernicus Marine Environment Monitoring Service (CMEMS) to be used as a unified point to map and assess MES in Lithuanian marine area. To map different indicators of MES such as wave weight and direction as well as chlorophyll-a concentration, data was extracted from physical and biogeochemical model outputs within CMEMS, covering the whole extent of the Lithuanian Exclusive Economic Zone. From a user perspective, the use of CMEMS to map and assess MES, allows: (1) to overcome complex challenges such as ecological modelling, utilizing outputs directly; (2) to cover spatial and temporal extent in areas where information is scarce and (3) to have vertically resolved data, important for the understanding and mapping of MES. In this perspective, CMEMS plays and will potentially play a higher role towards the operationalization of MES, contributing to better and more informed decision in the sphere of marine environmental management.

This work has received funding from the European Social Fund project Lithuanian National Ecosystem Services Assessment and Mapping (LINESAM) No. 09.3.3-LMTK-712-01-0104 under grant agreement with the Research Council of Lithuania (LMTLT).
High frequency stable isotope signals as proxy for physiological responses to climate - Dual isotope approach at a European scale
Authors: Vitali Valentina , Weigt Rosemarie , Klesse Stefan , Treydte Kerstin , Siegwolf Rolf , Saurer Matthias
Published: March 2020

Picea abies and Fagus sylvatica, are two of the most important tree species in Europe, and their responses to climate are being extensively investigated, especially at the limits of their distribution. However, their physiology at temperate sites is not yet fully understood. In a European tree-ring network, 10 sites along a climate gradient were sampled throughout Central Europe, and tree-ring width and stable isotope chronologies (C and O) were measured. The year-to-year variability of the isotopes time series for the last 100 years was analyzed in relation to tree-ring growth, spatial distribution, and seasonal climate.

Climate sensitivity of radial growth of both species was rather variable and site-dependent, and was strongest at the driest sites. On the contrary, variability in the isotopic ratios consistently responded to summer climate, particularly to vapor pressure deficit. The high δ18O coherence of the short-term variability between sites and species highlights the strength of the environmental signal in the O chronology also across long distances. On the contrary, δ13C shows lower correlations between sites and species, showing a stronger site-dependency, and a lower intra-annual variability. The generally positive correlation between the year-to-year differences in δ13C and δ18O across most sites demonstrates the strong role of stomatal conductance in controlling leaf gas exchange for these species. However, in the last decades, sites showed a dissimilar shift in the isotopes relationships, with the warmer sites showing an increase of either or both δ13C and δ18O and consequent decrease of photosynthetic rates and stomatal conductance, highlighting their dependency to atmospheric moisture demand and soil water availability.

Understanding the underlying physiological mechanisms controlling the short-term variation in tree-ring records will help with defining the performance of these ecologically and economically important tree species under future climate conditions.
Is carbonate sediment dissolution a significant source of dissolved organic matter to Florida Bay?
Authors: Zeller Mary , Van Dam Bryce , Lopes Chris , Smyth Ashley , Osburn Christopher , Kominoski John
Published: March 2020

Florida Bay is subtropical embayment characterized by dense Thalassia testudinum seagrass meadows, the prevalence of carbonate-rich sediments, and relatively long residence times (~1 yr). Florida Bay seagrass meadows store appreciable quantities of allochthonous and autochthonous organic matter (OM) as so-called ‘blue carbon’, the fate of which is therefore tied to that of the carbonate minerals it is bound to.  Dissolved organic carbon (DOC) concentrations are also relatively high (~7-12 mg/L), despite potential photo-oxidative loss in this shallow and long residence time system, as well as low internal DOC production due to the ecosystem’s documented oligotrophy.  These carbonate sediments can dissolve through net acid production via sediment heterotrophic processes as well as sulfide oxidation, processes which may be enhanced via O2 pumping through seagrass roots.  

This study investigated the impact of carbonate dissolution on the release of sediment-associated OM to surface waters, and the relative contribution of this process to surface water DOC quantity and quality.  We undertook a three-part experimental approach, with analyses including EEMs, δ13C-DOC, and FT-ICR-MS, to better understand the sources and fate of DOC in Florida Bay. 1) We conducted a spatial survey of surface waters, pore waters, and acid-leachable (representing the ‘carbonate-bound’ OM fraction) sedimentary OM.  2)  We conducted a DOM photodegradation study using two potential source surface waters, from a main tributary (Taylor Slough) and a central mangrove island.  3) We conducted benthic flux experiments using intact sediment cores facilitating direct measurements of the quality and quantity of DOC release from sediments. The flux information was placed into the context of sediment dissolution rates, estimated from coinciding determinations of alkalinity and inorganic carbon.

While analyses are ongoing, our initial results indicate a high degree of similarity between the fluorescence signature (PARAFAC components and fluorescence indices) of acid-leachable sedimentary OM, and that of DOC in pore water and surface water throughout Florida Bay.  Taken together, our study points to sediment dissolution as an important, yet understudied, process affecting organic carbon cycling in carbonate-dominated systems like Florida Bay.
Modelled Stokes drift in the Marginal ice zones of the Arctic Ocean
Authors: Li Jingkai
Published: March 2020

The Stokes drift in the marginal ice zones (MIZ) of the Arctic Ocean is modelled by WAVEWATCH III. Applying two viscoelastic and one empirical frequency-dependent wave-ice models, the modelled wave parameters and spectrum are compared with field observations in the Beaufort-Chukchi Sea. Three wave-ice parameterizations show similar abilities to produce the surface Stokes drift estimated from buoy measurements. By using five-year (2015-2019) hindcasted directional spectra of the autumn Arctic, we present and discuss the monthly mean surface Stokes drift (1-10 cm/s), e-folding depth (1-14 m) and vertically integrated transport (0.1-0.4 m2/s) in the marginal ice zones, which are stronger in October than in September. When bulk wave parameters are adopted to estimate the Stokes drift fields, the surface Stokes drift will be underestimated by about 44-59% with mean ice concentration smaller than 60%, and the Stokes e-folding depth will be overestimated by about 1.4 to 5.0 times increasing from the interior to the edge of the ice cover. Since the Stokes drift may be an important component of the total surface current, we compare the modelled surface Stokes drift with the Eulerian current from reanalysis data, which shows that the mean surface Stokes drift is typically about 30% of the Eulerian current over large parts of the MIZ in Arctic Ocean, and is of the same order or even larger in some sea areas of the Chukchi, E. Siberian and Laptev Seas. It indicates that the Stokes drift is necessary to be considered to better model the dynamic processes of the sea ice, especially for the drift of ice floes.
Manipulation experiments to infer the age and tracer composition of hydrologic fluxes
Authors: Asadollahi Mitra , Benettin Paolo , Nehemy Magali , Rinaldo Andrea , McDonnell Jeffrey
Published: March 2020

Several ecohydrological problems such as when and where precipitation becomes the source of plant uptake are usually tackled through stable isotope measurements. Our ability to go after these questions is often limited by field conditions that cannot be controlled, but targeted manipulation experiments can go beyond some of these limitations by imposing known boundary conditions and allowing the experimental closure of the isotope balance. This contribution presents examples from existing experiments that aim to understand which water, in terms of age and tracer composition, is uptaken by vegetation or drained to deeper soil horizons. In particular, we illustrate the Spike II experiment, which was carried out on a large vegetated lysimeter within the EPFL campus (CH) in 2018. This experiment featured the application of 40 mm of isotopically-enriched water on top of the lysimeter and its tracking for 40 days through the soil water, the lysimeter bottom drainage and the plant xylem. A total of more than 900 water samples were collected to reconstruct the “story” of the labeled precipitation. The detailed results from such controlled experiments represent a fundamental “ground truth” for our understanding of root water uptake patterns in large and diverse landscapes.
Impact of albedo and cloud retrievals on the NO2 tropospheric column derived from Sentinel-5P TROPOMI observations
Authors: Eskes Henk , Sneep Maarten , van Geffen Jos , Boersma Folkert , Wang Ping , Veefkind Pepijn
Published: March 2020

Sentinel-5P, with the TROPOMI instrument, was launched in October 2017 and is providing unique high-quality and high-resolution (5 km) observations of trace gas pollutants with a daily global coverage. In our contribution we will discuss the retrieval of nitrogen dioxide (NO2). A major contributions to the total uncertainty of these measurements are the TROPOMI retrievals of cloud fraction and effective cloud pressure (or altitude). Several cloud retrieval algorithms have been implemented, deriving cloud height information from the near-infrared O2-A band, O2-B band or the O2-O2 absorption feature near 477nm. In our presentation we will show the importance of a consistent treatment of clouds and albedo as input for the retrieval radiative transfer calculations. The impact of the different cloud products on the retrieved NO2 is demonstrated for a new implementation of the FRESCO O2-A band cloud retrieval algorithm and an implementation of the O2-O2 retrievals for TROPOMI. A recipe to make optimal use of the available cloud information is presented.
Fluid dynamic analog experiments on “Pele’s hair” using a handmade cotton candy machine
Authors: Kumagai Ichiro , Yamada Miyuki
Published: March 2020

On the south flank of Kilauea volcano in Hawaii Island, we will find glass fibers called “Pele’s hair” in the volcanic products of lava fountains and explosions. It is named after Pele, who is the Hawaiian goddess of volcanos. “Pele’s hairs” are highly stretched volcanic glass products, which are formed by breakup, stretching, and cooling of molten magma during their eruption. The texture of the glass fibers (thickness and length of fibers) depend on many parameters such as rheological properties of the volcanic glass, cooling rate, ejection speed, wind velocity, and so on. In order to consider the formation process of “Pele’s hair” in classroom experiments, we developed a handmade cotton candy maker. We used a commercial stirrer which could control the rotating speed. At the edge of the stirrer, we attached a rotating dish, which was made of thin steel and had small outlets along its periphery. To make fibers of sugars (threads of cotton candy), crystal sugar (“Za-ra-me” in Japanese, coarse sugar) was added to the dish and rotated at a constant speed. The melted sugar was formed after heating the rotating disk and ejected through the outlets. We measured the temperature of the melted sugar by a commercial radiation thermometer and the flow behavior of the melted sugar jet was captured by a high-speed video camera, which helped us to understand the formation process. By controlling the rotating speed, heating temperature and diameter of the outlets, we have succeeded in producing a variety of analog “Pele’s hair” and Pele’s tear”. We carefully examined the texture of the analogue Pele’s products and discussed the role of these controlling parameters on their formation process. In this presentation, we will also discuss the similarity of the texture of Pele’s hairs, which were sampled from volcanic products in Hawaii Islands, with the analog Pele’s hairs of cotton candy using a commercial digital microscope.
Guiding Sustainable Development along Rivers in India
Authors: Bais Roshni , Suneja Manavvi
Published: March 2020

Rivers have been a crucial part of human existence and the cradle of ancient civilizations. Historically, all cities developed along river banks. Rivers have played a seminal role in structuring cities the world over. India is recognized as a river nation and has had a long history of mystical affiliation with its rivers. Here rivers are considered sacred and venerated. All human activities and rituals are innately associated with the riverfront. Riverfronts have functioned as crucial socio-cultural religious spaces. In today’s times however Rivers present a gory picture of neglect. Fresh water is polluted by domestic, industrial, agricultural and religious waste. Fortunately, people  over the world have begun to realize the importance of rivers and concentrated efforts to ecologically rehabilitate and restore them are underway. In India, such efforts are mostly hinged on channelizing the riverbank and providing a space for recreation for city dwellers. Activists and water proponents, however, contest this approach and term it to be a mere initiative focussed towards river beautification rather than river rehabilitation. Such initiatives are not necessarily ecologically responsive and sustainable. India has been one of the leading participants of the United Nations and is dedicated to the UN's 2015 sustainable development goals (SDGs). Under SDG 6 and SDG 11, India strives to boost its water bodies, water quality and provide a comprehensive sustainable solution. India initiated the Smart City Projects (SCP's) in 2015, focussing on cities ' overall sustainable development'. Under this project, a total of 100 cities have been identified and more than 60 cities have a plan for riverfront development. These initiatives are targeted at reducing water pollution, providing aid to the riverbank and improving the connect between the city and its river. This paper aims at reviewing the recent Riverfront development proposals in India under the smart city mission and develop a set of indicators as a framework that allows future communities to reclaim their river and river edges in a sustainable manner. Research is conducted in two stages. Phase one is to establish a framework based on the principles of urban design and urban planning policies in India and assess the planned riverfront project. Phase two suggests a multi-criterion sustainability framework in the context of Indian rivers and validate its application using the community discussion process. Discussions involve Indian government officials’ scholars from a variety of disciplines, engineers, designers, and the general public. This framework aims to direct developers, architects, PWDs, environmental authorities, towards sustainable restoration/rehabilitation strategies in the context of Indian rivers. 

Keywords: Riverfront development, River Rehabilitation, River Restoration, Sustainability, Channelization, Smart City Projects
The implications of soil erosion model conceptualization, bias-correction methods and climate model ensembles on soil erosion projections under climate change
Authors: de Vente Joris , Eekhout Joris
Published: March 2020

Climate models project increased extreme precipitation for the coming decades, which may lead to higher soil erosion in many locations worldwide. The impact of climate change on soil erosion is most often assessed by applying a soil erosion model forced by bias-corrected climate model output. A literature review among more than 100 papers showed that many studies use different soil erosion models, bias-correction methods and climate model ensembles. In this study, we assessed how these differences affect the outcome of climate change impact assessments on soil erosion. The study was performed in two contrasting Mediterranean catchments (SE Spain), where climate change is projected to lead to a decrease in annual precipitation sum and an increase in extreme precipitation, based on the RCP8.5 emission scenario. First, we assessed the impact of soil erosion model selection using the three most widely used model concepts, i.e. a model forced by precipitation (RUSLE), a model forced by runoff (MUSLE), and a model forced by precipitation and runoff (MMF). Depending on the model, soil erosion in the study area is projected to decrease (RUSLE) or increase (MUSLE and MMF). The differences between the model projections are inherently a result of their model conceptualization, such as a decrease of soil loss due to decreased annual precipitation sum (RUSLE) and an increase of soil loss due to increased extreme precipitation and, consequently, increased runoff (MUSLE). An intermediate result is obtained with MMF, where a projected decrease in detachment by raindrop impact is counteracted by a projected increase in detachment by runoff. Second, we evaluated the implications of three bias‐correction methods, i.e. delta change, quantile mapping and scaled distribution mapping. Scaled distribution mapping best reproduces the raw climate change signal, in particular for extreme precipitation. Depending on the bias‐correction method, soil erosion is projected to decrease (delta change) or increase (quantile mapping and scaled distribution mapping). Finally, we assessed the effect of climate model ensembles on soil erosion projections. We showed that individual climate models may project opposite changes with respect to the ensemble average, hence, climate model ensembles are essential in soil erosion impact assessments to account for climate model uncertainty. We conclude that in climate change impact assessments it is important to select a soil erosion model that is forced by both precipitation and runoff, which under climate change may have a contrasting effect on soil erosion. Furthermore, the impact of climate change on soil erosion can only accurately be assessed with a bias‐correction method that best reproduces the projected climate change signal, in combination with a representative ensemble of climate models.
Kite - bridging InSAR displacement analysis and earthquake modelling: the 2019 Ridgecrest earthquakes
Authors: Isken Marius Paul , Sudhaus Henriette , Heimann Sebastian , Vasyura-Bathke Hannes , Steinberg Andreas , Dahm Torsten
Published: March 2020

We present a modular open-source software framework - Kite (http://pyrocko.org) - for rapid post-processing of spaceborne InSAR-derived surface displacement maps. The software enables swift parametrisation, post-processing and sub-sampling of the displacement measurements that are compatible with common InSAR processors (e.g. SNAP, GAMMA, ISCE, etc.) and online processing centers delivering unrwapped InSAR data products, such as NASA ARIA or LiCSAR. The post-processing capabilities include removal of first-order atmospheric phase delays through elevation correlation estimations and regional atmospheric phase screen (APS) estimations based on atmospheric models (GACOS), masking of displacement data, adaptive data sub-sampling using quadtree decomposition and data error covariance estimation.

Kite datasets integrate into forward modelling and optimisation frameworks Grond (Heiman et al., 2019) and BEAT (Vasyura-Bathke et al., 2019), both software packages aim to ease and streamline the joint optimisation of earthquake parameters from InSAR and GPS data together with seismological waveforms. These data combinations will improve the estimation of earthquake rupture parameters. Establishing this data processing software framework we want to bridge the gap between InSAR processing software and seismological modelling frameworks, to contribute to a timely and better understanding of earthquake kinematics. This approach paves the way to automated inversion of earthquake models incorporating space-borne InSAR data.

Under development is the processing of InSAR displacement time series data to link simultaneous modelling of co- and post-seismic transient deformation processes from InSAR observations to physical earthquake cycle models.

We demonstrate the framework’s capabilities with an analysis of the 2019 Ridgecrest earthquakes from InSAR surface displacements (provided by NASA ARIA) combined with GNSS displacements using the Bayesian bootstrapping strategy from the Grond inverse modelling tool.
Coupled Computational Fluid Dynamics (CFD) and Artificial Neural Network (ANN) for Prediction of Traffic-related Air Pollution Infiltration Effects in Hong Kong
Authors: Nieborowski Fritz
Published: March 2020

Improper ventilation of buildings may lead to an accumulation of pollutants indoors. In the case of a room with forced air ventilation and external air intake like most centralized and some home air conditioning units, this study will show CFD simulations of various indoor air quality conditions based on different forced ventilation AC unit intake conditions like common in housing situations like Hong Kong. Especially when close to roadways or other external pollution sources, the positioning of the air intake shows up to have a high significance for the infiltration rate resulting as influence for the indoor air quality as previous research shows (e.g. Zheming Tong et al., 2016). The same is the case for a forced ventilation case like air conditioning units with outside air intake. Research like earlier referenced paper has not been conducted with higher buildings or forced air intake yet. Parametrized CFD-based air quality models with using OpenFoam will be employed to quantify the impact of the air intake location and rate in a 2-dimensional interface on the indoor air quality of a forced ventilated section of a building. The findings of the CFD simulation will be simplified as average indoor air pollution and other external factors. As an approach to predict the estimate indoor infiltration rate, an ANN (Artificial Neuronal Network) will be used, trained and validated with said data. The neural network is supposed to predict the pollutant intake based on fewer and as easier to obtain meteorological parameters and air pollution data. Finally, the ANN predictions of the models will be verified with real life data from other papers. Results will show that a major part of indoor pollutants may emerge indoors and cannot be neglected. In comparison with real life data, it seems the model lacks significant input to predict with high accuracy. 
Arctic connections between sea ice, ocean dynamics and biogeochemistry in the UK Earth System Model (UK ESM1): present climate and future scenarios
Authors: Aksenov Yevgeny , Yool Andrew , Palmieri Julien , Popova Katya , Kelly Stephen , Rynders Stefanie , Schroeder David , Sinha Bablu
Published: March 2020

We present analysis of Arctic sea ice and ocean dynamics in the ensemble of the UK Earth System Model (UK ESM1) simulations completed under the Coupled Model Intercomparison Project Phase 6 (CMIP6) protocol. The focus of the investigation is on the future changes in the Arctic sea ice and oceanic connections and on the impact of the nutrient advection on the Arctic marine biogeochemistry and ecosystems. Changes in the balance of the oceanic inflows from the North Atlantic and North Pacific Oceans are found to have a first order effect on the watermasses and nutrients balances in the central Arctic Ocean. The simulations show that the total primary production in the Arctic Ocean is increased by 100% in the 2090s as compared to the present climate. This is caused by higher nutrients availability in the Atlantic inflowing waters and prolonged ice- free season. The faster connections through the Arctic and milder oceanic environment allows species to survive through the winter and from the second half of the century the Arctic Ocean could become a key oceanic gateway connecting the global oceans. The study is supported from the project APEAR (NE/R012865/1) NERC-BMBF and from the NERC ACSIS Programme (NE/N018044/1).
Shaping Planetary Surfaces: The Impact of Liquid and Frozen Water on Hillslope Topography
Authors: Smith Taylor , Bookhagen Bodo
Published: March 2020

The availability of liquid water plays a primary role in controlling the development of topography. Hillslope asymmetry (HA), or slope differences between terrain aspects, has been well-documented in small-scale and field-based studies throughout the world. In this study, we apply a consistent HA analysis method across the entire globe and find that poleward facing hillslopes are on average steeper than equator-facing hillslopes, with the exception of high-latitude, high-elevation, and low-temperature regions where equator-facing slopes tend to be steeper.

To test the impact of different land cover and climate regimes on HA, we use global and high-resolution elevation, vegetation and land-surface temperature data to examine erosional process differences between poleward- and equator-facing hillslopes. We find that vegetation supports poleward-steepening, and that low temperatures and high freeze-thaw cycle frequencies enhance equator-steepening of hillslopes. We further show that HA is propagated into the size and form of fluvial drainage networks. We posit that insolation plays a key role in controlling soil-water availability and retention, and thus drives asymmetries in vegetation cover, soil formation rates and landscape form at the planetary scale.