bluuebunny/crossref_metadata_2025 huggingface dataset:
Street Scale Air Pollution Modelling in Antalya on Mediterranean Coast of Turkey
Authors: tepe ahmet mustafa , Ketzel Matthias , Im Ulaş , Doğan Güray
Published: March 2020

Antalya is a city at the Turkish Riviera located on Mediterranean coast of southwestern Turkey and it is the fifth populated city in Turkey. The city has a downtown population of over 2 million. Agriculture and tourism activities are the most important sources of income in the region. Antalya is a very important tourism destination and welcomes more than 10 million tourists every year.

Nowadays, with the rapid increase in urbanization, air pollution has been one of the most important environmental problems especially in big cities. In order to solve the pollution problems as soon as possible, the largest air pollution sources must be determined first. Air quality models are used extensively in air quality studies as they allow these problems to be identified quickly, cheaply and effectively. The semi-parameterized Operational Street Pollution Model (OSPM®) has been widely used around the globe to determine levels of air pollution on local or street-scale for urban street canyons (Berkowicz 2000, Ketzel et al. 2012).

For this study; four street canyons along the main roads in central Antalya were selected (100. Yıl Avenue, Yener Ulusoy Avenue, Adnan Menderes Avenue, Kızılırmak Street).  Modeling has been carried out for a period of one year (July 2014 – July 2015) for the pollutants PM2.5 and PM2.5-10.

The urban background concentrations for particulate matter (PM2.5 and PM2.5-10) were collected using stack filter unit system. Total of 169 samples were collected once in a two-day period between July 2014 and July 2015 (Tepe 2016). Meteorological parameters and traffic data used in this study were obtained from Turkish State Meteorological Service and Turkish Statistical Institute, respectively.

REFERENCES

Berkowicz, R. OSPM - A Parameterised Street Pollution Model. Environ. Monit. Assess. 65, 323 331 (2000)

Ketzel M, Jensen SS, Brandt J, Ellermann T, Olesen HR, Berkowicz R and Hertel O. Evaluation of the Street Pollution Model OSPM for Measurements at 12 Streets Stations Using a Newly Developed and Freely Available Evaluation Tool. J Civil Environ Eng, S1:004 (2012)

Tepe, A. Investigation of Concentrations and Source Apportionment of Metals Attached to PM2.5 and PM10 in Antalya Ambient Air (Unpublished master’s thesis). Akdeniz University, Antalya, Turkey (2016)
Estimating local methane sources from drone-based laser spectrometer measurements by mass-balance method
Authors: Morales Randulph P. , Ravelid Jonas , Brennan Killian P. , Tuzson Béla , Emmenegger Lukas , Brunner Dominik
Published: March 2020

Methane from facility-scale sources (e.g. landfills and oil and gas production facilities) are prone to leakage giving rise to highly uncertain emission flux estimates. To assess the overall impact of these sources, quantification from a representative set of individual sources – from which bottom-up inventories are generated - is necessary. An attractive approach to quantify emissions from diffusive and leaky sources involves deploying an unmanned aerial vehicle (UAV) equipped with a methane sensor which allows complete mapping of the spatial and temporal variability of emission plumes within a short period of time.

Atmospheric methane concentrations were measured using a Quantum Cascade Laser Absorption Spectrometer (QCLAS) developed in-house. The spectrometer reaches in-flight precision of a few ppb at 1s time resolution, and its lightweight and compact footprint (~ 2.0 kg, ~ 15.0 x 45.0 x 25.0 cm) allows it to be mounted and flown on a commercial drone.

We quantify methane emission fluxes from local sources by applying the mass balance method using the drone-based QCLAS system. The drone was flown downwind of a given source perpendicular to the main wind direction at different altitudes above ground, while geostatistical interpolation (Kriging) of the measured methane molar fractions was performed to spatially fill the gaps. The interpolated concentrations were multiplied by the cross-sectional area and the mean stream-wise wind profile obtained from a 3D sonic anemometer to get an emission flux.

We report on the analysis of how well known emissions can be reproduced using this quantification setup based on controlled release experiments. Furthermore, we discuss the sensitivity of different measurement configurations, and provide recommendations for an optimal sampling and quantification strategy. We demonstrate the suitability and flexibility of the quantification method in investigating a wide range of facility-scale sources, which are not attainable with measurements from conventional ground-based sensors.
Spatial and temporal distributions of NO2 and aerosols over the urban environment of Vienna during the VINDOBONA project (2017-2019)
Authors: Schreier Stefan , Richter Andreas , Bösch Tim , Lange Kezia , Revesz Michael , Hilboll Andreas , Peters Enno , Vrekoussis Mihalis , Weihs Philipp , Schmalwieser Alois , Burrows John
Published: March 2020

Within the scope of the VINDOBONA (VIenna horizontal aNd vertical Distribution OBservations Of Nitrogen dioxide and Aerosols) project, spectral UV/vis measurements at selected viewing directions are performed with three MAX-DOAS (Multi AXis Differential Optical Absorption Spectroscopy) instruments, which are located in the northeast, northwest, and south of the city center of Vienna, Austria. The selection of viewing directions of the three instruments was chosen in a way to provide data for the retrieval of horizontal and vertical trace gas and aerosol distributions, in particular over the urban core.

In the present work, the profile retrieval algorithm BOREAS (Bremen Optimal estimation REtrieval for Aerosols and trace gaseS) is used to retrieve aerosol and NO2 vertical profiles as well as accompanying parameters aerosol optical depth, tropospheric NO2 vertical columns (TVC NO2), and near-surface NO2 on days with cloudless conditions. The retrieval results are compared with co-located ceilometer, sun photometer, surface air quality, and TVC NO2 measurements, with the latter being obtained by applying the geometrical approximation and converting zenith-sky NO2 measurements.
Hydrodynamic modelling of compound flood drivers in estuaries
Authors: Couasnon Anais , Eilander Dirk , Bates Paul , Winsemius Hessel C. , Ward Philip J.
Published: March 2020

Compound flooding in deltas and estuaries can be defined as the combination of various flood drivers leading to a significant flood impact (Zscheischler et al., 2018). For example, elevated sea-levels can impede flood drainage and create backwater effects that worsen flood damages. This was observed recently in March 2019 during cyclone Idai, where devastating floods from a high storm surge and discharge destroyed the port city of Beira. Even though the importance of accounting for compound flooding in flood risk assessments has been heavily underlined in recent literature, little research has been done on the impacts of compound flood events globally.

In this study, we investigate how compound flood hazard in estuaries is influenced by their various geophysical characteristics and the nature of their upstream river basins. The influence of riverine and coastal flood drivers on the water level varies along the estuary.  The water level at the river mouth is dependent on sea-levels, whereas one can expect this influence to reduce moving upstream in the river system and to become negligible completely upstream in large river systems. The location within a river system where both riverine and coastal flood drivers significantly contribute to the water level is referred to as the transition zone (Bilskie and Hagen, 2018).

We set up a model experiment to compare maximum water levels across realistic estuary types and boundary conditions. We use the 1-D unsteady hydrodynamic model LISFLOOD-FP to simulate water level time series for average and anomalous compound flood events of sea-levels and discharge. For each estuary type, resulting water level time series are analyzed to quantify the contribution of each flood driver in the maximum water level obtained along the complete coastal river profile and on the extent of the transition zone. We find that the interaction between the extreme sea level and extreme discharge is highly nonlinear and that this effect strongly varies depending on the estuary shape and length. We foresee this extensive overview of estuarine compound flood behavior to globally identify areas particularly vulnerable for interactions between extreme discharge and sea levels.
Lessons learned on atmospheric radon modelling by statistical model-to-data comparison on gamma dose rate peaks
Authors: Quérel Arnaud , Quélo Denis , Doursout Thierry , Gréau Claire
Published: March 2020

Radon-222 is a progeny of Uranium-238, naturally present in the Earth’s crust. After its migration through the soil, it reaches the atmosphere. The Radon progenies are then adsorbated to aerosol particles. The particles are scavenged by falling rain drops, leading a large amount of radon progenies to the ground. This sudden addition of radon progenies explains to the gamma dose rate peaks occurring during rainfall events.

An atmospheric radon modelling chain was developed. It is based on the IRSN long-range atmospheric transport modelling, and can be used to forecast or to reanalyze these events. The peaks are observed hundreds times a year on radioactivity monitoring networks in France. Then, a comprehensive statistical comparison can be achieved to evaluate the modelling, in particular its atmospheric transport component.

Less than half of the gamma dose rate peaks simulated matches the observed ones. We considered false positive – peaks simulated but not observed – and false negative – peaks observed but not simulated. Radon exhalation spatial distribution and seasons seem to have a major impact on the model capability to reproduce these peaks. The choice of rain data is also essential for a better simulation.

Beyond other validation cases, IRSN now has a validation tool, the database of which is populating on a daily basis, to evaluate the long-range atmospheric transport model used for emergency purposes. The quality of this response is a critical issue and has to be constantly improved. The statistics on the gamma dose rate peaks will improve our understanding of the phenomena. It will also be used to validate the improvement made on the accuracy of the radon exhalation spatial distribution.
Climate hazard indices projections based on CORDEX-CORE, CMIP5 and CMIP6 ensemble.
Authors: Coppola Erika ,   CORDEX-CORE
Published: March 2020

Under the CORDEX umbrella the CORDEX-CORE initiative has been developed that was able to produce an ensemble of two RCMs at 0.22° resolution downscaling 3 GCMs for each of the 9 CORDEX domains for two climate scenarios the RCP2.6 and the RCP8.5. The CORDEX-CORE and the CMIP5 driving ensemble together with the most recently produced CMIP6 ensemble has been analyzed and several temperature, heat, wet and dry hazard indicators have been computed for the present day and mid and far future time slices.

As a results CORDEX-CORE shows a better validation for several hazard indices due to the higher spatial resolution. For the far future time slice the 3 ensembles project an increase for all the temperature and heat indices under the RCC8.5 scenario. The highest values are always shown by the CMIP6 ensemble except that for Tx>35 °C for which CORDEX-CORE projects higher warming. Extreme wet and flood prone maxima are projected by the regional ensemble over la Plata basin in South America , over the Congo basin in Africa, in east North America, north east Europe , India and Indochina, notably the regions where a better validation is obtained, whereas the global ensembles show quite small or not existent signal. Compound hazard hotspots based on heat and drought indicators have been identified in Central America, in the Amazon region, in the Mediterranean, South Africa, India and Australia since in all these regions a linear relation is shown by the heatwave and drought change signal. Although still limited the CORDEX-CORE initiative was able to produce high resolution climate projections with a quasi global coverage. This can be seen as a first step to foster collaboration among the global and regional climate community. The existence of the first of this kind ensemble together with the previous CORDEX 0.44 ensembles and the global ensemble is very valuable for climate impact assessment studies since can provide information on the mean and extreme regional climate projections but also more robust quantification on the model spread. All being an added value for the impact and climate services communities.
Distribution and fractionation of light hydrocarbons related to gas hydrate occurrence and biogenic production at Hikurangi Margin (IODP Site U1517), New Zealand
Authors: Heeschen Katja , Schloemer Stefan , Torres Marta , Cook Ann E , Screation Liz , Georgiopoulou Aggeliki , Pecher Ingo , Mayanna Sathish , Barnes Phil , Solomon Evan , LeVay Leah
Published: March 2020

The investigation of the gas hydrate system and hydrocarbon distribution were targets of IODP expeditions 372 and 375 on the Hikurangi Margin offshore New Zealand. Isotopic and molecular signatures clearly indicate a biogenic signature of methane at all sites drilled along a section crossing the accretionary wedge and basin sediments. The gas void and headspace samples from depth of a few meters up to 600 m below the seafloor have varying amounts of light hydrocarbons with high amounts of methane and changing ratios of C2:C3. The best example is the high-resolution profile gained from gas voids collected at Site U1517. Drilling at U1517 reached through the creeping part of the Tuaheni Landslide Complex (TLC), the base of the slide mass, and the Bottom Simulation Reflector (BSR) just above the base of the hole. Whereas gas hydrates could not be observed macroscopically, the distribution of gas hydrates was determined by logging while drilling (LWD) and pore water data revealing the occurrence of gas hydrates at roughly 105 – 160 mbsf with elevated saturations in thin coarse-grained sediments. The application of cryo-Scanning Electric Microscopy (cryo-SEM) on samples preserved in liquid nitrogen enabled the visualization of gas hydrates.

 

At Site U1517 the high-resolution void sampling reveals molecular and isotopic fractionation of hydrocarbons in close relation to the gas hydrate occurrences and allows for drawing conclusions on the recent history of the gas hydrate system and absence of free gas transport from below at the site. The molecular and isotopic composition further indicates ongoing propanogenesis.
Towards an ensemble-based assimilation of boundary-layer observations for soil moisture
Authors: Finn Tobias Sebastian , Geppert Gernot , Ament Felix
Published: March 2020

The temporal and spatial development of the atmospheric boundary layer is coupled to soil conditions via latent and sensible heat flux. Information about soil conditions is following encoded in atmospheric screen-level observations. To infer the soil moisture, these observations are usually assimilated with a Simplified Extended Kalman Filter (SEKF). This data assimilation technique is simplified in comparison to Ensemble Kalman Filters (EnKF), which are often used for data assimilation in the atmosphere. To make full use of the interface between atmosphere and land, we want to use strongly-coupled data assimilation with a unified system. We will present which problems have to be solved within an EnKF framework to use it as unified data assimilation system. We initialized an observing system simulation experiment with the TerrSysMP system, where a limited area model for the atmosphere is coupled with the Community Land Model. Here, we assimilate the two-metre temperature with an EnKF to update the soil moisture for a dry time period. We use initial soil moisture and soil temperature perturbations as only method to create an ensemble.

We show a positive observation impact during daytime. The analysis and forecast are further improved compared to assimilation with a SEKF. During daytime, the atmosphere and soil are strongly coupled, while they are almost uncoupled during night-time. Following, we have a slightly negative observation impact during night-time. This negative impact is induced by sampling errors of the ensemble. The negative impact is further amplified in the transition time between night and day. We can attribute this amplification to horizontal heterogeneities and multiplicative ensemble inflation in soil. We can therefore say that the inflation is wrongly tuned for the soil during night-time, while it works for the atmosphere and during daytime. We hypothesize that these problems during night-time can be avoided by using additional models, like a time-dependent localization radius and inflation factor.
Wind erosion in Moroccan argan woodlands under extensive agro-silvo-pastoral management
Authors: Marzen Miriam , Mario Kirchhoff , Irene Marzolff , Ali Aït Hssaine , Ries Johannes B.
Published: March 2020

The Moroccan argan woodlands form a unique ecosystem that is at acute risk of degradation and desertification. Beside the great impact on local and regional socio-economical structure, the characteristic landscape is assumed to protect populated and agriculturally productive areas such as the Souss-Massa-region against desertification processes from the adjacent desert areas in Southwest Morocco and Algeria.

The experimental-empirical study with the Trier Portable Wind Simulator was conducted to quantify sediment mobilisation by wind on various surface characteristics associated to argan woodlands under extensive agro-silvo-pastoral management. Tested surfaces included physical and biological crusts, stone and litter cover and ploughed surfaces.

We found that the argan woodlands of the Souss region may be a significant source of wind eroded sediment particularly facing effects of overexploitation and climate change. An adapted land management is key to prevent severe dust production and mitigate possible impacts of land use change and climate change related shifts in wind and rainfall patterns.  
Urbanisation of weather data lead for more sustainable building design: urban land surface model used to generate Typical Meteorological Year (TMY) datasets
Authors: Sun Ting , Tang Yihao , Xiong Jie , Omidvar Hamidreza , Grimmond Sue
Published: March 2020

Typical Meteorological Year (TMY) datasets are widely used in building energy design simulations to assess needs (cooling/heat). Currently, TMY data used are representative of the past climate (from observations) of the region and generally do not account for urban climate or building-city interactions. Here we use an urban land surface model, SUEWS (Surface Urban Energy and Water Balance Scheme) driven by ERA5 reanalysis data to bridge this gap.

Using 0.25 ° large-scale ERA5 reanalysis data (1979–2018) with SUEWS we generate an urbanised TMY (uTMY) dataset for Changsha, a city with more than 4.4 million residents in the hot-summer-cold-winter region of China, to demonstrate the proposed workflow. The SUEWS simulation are evaluated at the Leifeng site (WMO code 57687) for 2016.

Through comparison of DOE EnergyPlus simulations, we also assess the impact on design building energy consumption using uTMY and cTMY (conventional TMY) data. The building design energy needs evaluation is for a common Chinese apartment building. This should allow for more spatially explicit building design, and hence more sustainable.
GAUSS - A Sample Return Mission to Ceres
Authors: Shi Xian ,   GAUSS Project Team
Published: March 2020

Ceres, the largest resident in the main asteroid belt and the innermost dwarf planet of the solar system, shares characteristics with a broad diversity of solar system objects, making it one of the most intriguing targets for planetary exploration. The recently completed Dawn mission through its 3.5 years of in-orbit investigation has furthered our understanding of Ceres, yet at the same time opened up more questions. Remote sensing data revealed that Ceres is rich in volatiles and organics, with fresh traces of cryovolcanic and geothermal activities. There is potential evidence of Ceres’ past and present habitability. Findings by Dawn suggest that Ceres might once be an ocean world and have undergone more complicated evolution than originally expected. Thus, Ceres encapsulates key information for understanding the history of our solar system and the origin of life, which has yet to be explored by future missions.

We present the GAUSS project (Genesis of Asteroids and EvolUtion of the Solar System), recently proposed as a white paper to ESA’s Voyage 2050 program. GAUSS is a mission concept of future exploration of Ceres with sample return as the primary goal. It aims to address the following top-level scientific questions concerning: 1) the origin and migration of Ceres and its implications on the water and volatile distribution and transfer in the inner solar system; 2) the internal structure and evolution of Ceres; 3) Ceres’ past and present-day habitability; and 4) mineralogical connections between Ceres and collections of primitive meteorites. We will discuss scientific objectives of Ceres exploration in post-Dawn era as well as instrumentation required for achieving them. We will explore candidate landing and sampling sites of high scientific interest based on Dawn results. We will also consider technical and financial feasibility of different mission scenarios in the context of broad international collaboration.
Using Sentinel-1 and -2 satellite time series to monitor crop phenology at the parcel level
Authors: d'Andrimont Raphaël , Lemoine Guido , van der Velde Marijn
Published: March 2020

Phenology can contribute to many scientific disciplines from climate change, biodiversity, agriculture and forestry to human health. The knowledge of timing of phenological events and their variability can provide valuable data for agriculture. Accurate and timely information on the dates of specific stages of crop development is needed for various applications including crop yield forecasting. Despite the proven capabilities of Sentinel satellites for crop mapping and estimating phenology, they have not yet been applied effectively for tracking crop development across large areas. 

A methodology is proposed to systematically identify phenology phases from time series generated by the Copernicus Sentinel-1 (S1) and Sentinel-2 (S2) sensors. This is done by linking specific agricultural-parcel temporal S1 and S2 signatures to phenology observations representative for 5-km buffers around the 6573 Deutscher Wetterdienst (DWD) stations spatially distributed across Germany. First, a S1-based 10-m crop type classification was made around each DWD station trained with LUCAS (Land Cover and Land Use Area frame Survey) 2018 data which allowed identifying parcels as well as crop types. Second, the average crop specific S1 (VV and VH) and S2 (NDVI) temporal signal is extracted for each DWD station and the correlation between the DWD BBCH event and characteristic behaviour in the satellite signals such as dips or peaks is systematically assessed for each crop. 

This approach identified the unique and crop-specific temporal signatures of S1 and S2 associated with specific phenology events such as emergence, flowering or ripening. We further discuss the potential and limitations of S1 and S2 to extract this type of information. These temporal S1 and S2 signatures can contribute to a digital reference library that could be used to monitor crop phenology operationally for parcels across the globe. Moreover, it unveils the potential of S1 and S2 to study detailed spatial and temporal gradient of crop phenology in the light of climate change.
Bridging the gap – linking GRACE and GRACE-Follow On by hlSST and SLR
Authors: Weigelt Matthias , Jäggi Adrian , Meyer Ulrich
Published: March 2020

GRACE and GRACE-Follow On are the standard tools for observing the time variable gravity field. Unfortunately, there is no overlap of the two time series of monthly gravity field solutions due to the ending of the GRACE mission in 2017 before the first monthly solutions of GRACE-Follow On became available in June 2018. Thus, there is a need for an intermediate technique that will bridge the gap between the two missions and will allow 1) for a continued and uninterrupted time series of mass observations and 2) to compare, cross-validate and link the two time series. As a bridging technology hlSST/SLR combinations are arguably the most promising candidate. We presented earlier combinations of those based on 41 kinematic orbit products of 27 satellites and 9 SLR satellites. Here, we progress to the next step and present results where we use the combined hlSST/SLR solution within a Kalman environment to link GRACE to GRACE-Follow On via the hlSST/SLR time series. The combination is conducted on coefficient level: after reducing the climatology derived from GRACE, a modified continuous Wiener process acceleration (CWPA) model is employed as the driving dynamic model of the Kalman filter for the prediction step. Subsequently the predicted time step is updated by (residual) observations when available. The resulting time series is thus complete for all months starting from April 2002 till today. We will discuss the benefit and limitations of the approach. The research is conducted within the framework of the International Gravity Field Service (IGFS) product center (COST-G) which is dedicated to the combination of monthly global gravity field models.
The airport-sCAle seveRe weather nowcastinG prOject (CARGO)
Authors: Biondi Riccardo , Tournigand Pierre-Yves , Solazzo Enrico , Realini Eugenio , Cimarelli Corrado , Kauczok Sebastian
Published: March 2020

Monitoring and predicting extreme atmospheric events, such as deep convective systems, is very challenging especially when they develop locally in a short time range. Despite the great improvement in model parametrization and the use of satellite measurements, there are still large uncertainties on the knowledge of the dynamical processes of deep convective systems at local scale.

We use an innovative approach integrating a dense network of in situ measurements and satellite-based observations/products for the improvement of meteorological nowcasting at airport spatial scale focusing on the Malpensa airport (Italy). We add to the standard atmospheric parameters analysis, the information of integrated water vapour and lightning spatio-temporal behaviour (potential heavy rain precursors) during heavy rain phenomena detected by meteorological radars. The study is based on the anomaly of each atmospheric parameter during a convective event in comparison to its climatology in non-pre-convective environment, so that we are able to detect the variation with respect to the “standard” conditions. The ground based GNSS receivers (allowing the determination of the integrated water vapour trend before and during the storm), together with the lightning detectors, the weather stations (providing the trend of temperature, humidity and wind fields), the radiosondes and the GNSS radio occultations (allowing the estimation of vertical profiles of temperature, pressure and humidity) provide information on the pre-convective and non-pre-convective environment as a 3D picture of the atmospheric conditions.

The final goal is the test of a severe weather events nowcasting algorithm with high spatial resolution, and based on neural networks, for improving aviation safety. This is followed by the development of a user-friendly tailored final product, easily understandable by the Air Traffic Management stakeholder.

We have collected more than 600 cases suitable to develop the neural network algorithm. We show here the algorithm implementation and the meteorological characterization of deep convection usually developing on the Malpensa airport area.
Stable boundary layer height on a gentle slope
Authors: Stiperski Ivana , Holtslag Albert A.M. , Lehner Manuela , Whiteman C. David
Published: March 2020

Height of the stable boundary layer (SBL) presents an important diagnostic used to describe the relevant processes governing the evolution and characteristics of SBL, and the extent to which the surface is communicating with the free atmosphere.  Here we investigate the SBL height over a gentle (1°) mesoscale slope on which relatively deep mid-latitude katabatic flows (with jet maxima between 20 and 50 m) develop during clear nights. We show that detecting the SBL top depends on the method used (Richardson number, flux- and anisotropy-profiles). The detected SBL depth, mostly deviates from the jet maximum height or the top of the near-surface inversion. The flat terrain formulations for the SBL height correlate well with the detected top of the SBL if instead of background stratification, near-surface stratification is used in their formulations, however, they mostly largely overestimate the SBL height. The difference to flat-terrain SBL is also shown through the dependence of size of the dominant eddy with height. In katabatic flows the eddy size is semi-constant with height throughout the SBL, whereas in flat terrain eddy size varies significantly with height.
Hotspot swells and the lifespan of volcanic ocean islands
Authors: Huppert Kimberly , Perron J. Taylor , Royden Leigh
Published: March 2020

The seafloor surrounding ocean hotspots is typically 0.5 - 2 km shallower than expected for its age over areas hundreds to >1000 km wide, but the processes generating these bathymetric swells are uncertain. Two end-member models have been proposed to explain swell uplift. The first model, lithospheric thinning, posits that reheating of the lithosphere causes the seafloor to uplift due to the isostatic effect of replacing colder, denser lithosphere with hotter, less dense upper mantle. The second model, dynamic uplift, proposes that swells are supported by upward flow of ascending mantle plumes and/or hot, buoyant plume material ponded beneath the swell lithosphere. If swells are dominantly produced by lithospheric thinning, the resulting thermal subsidence should approximately mimic the subsidence of young ocean lithosphere. This places an upper bound on the rate of seafloor and island subsidence following swell uplift, since conductive cooling of the lithosphere is a gradual process. On the other hand, if swell topography is dominantly produced by dynamic uplift, then seafloor subsidence depends primarily on how rapidly plate motion carries the seafloor off the swell and the spatial extent of the swell.

Because these two models predict different patterns of seafloor and island subsidence, swell morphology and the geologic record of island drowning may reveal which of these mechanisms dominates the process of swell uplift. To test this, we isolated regional swell bathymetry at 14 ocean hotspots. Considering the end-member case of lithospheric thinning, we modeled the thermal evolution of the lithosphere at each hotspot following swell uplift, and we compared the resulting thermal subsidence to observed swell subsidence. We also estimated island residence times atop swell bathymetry (swell length/plate velocity), and we compared this residence time to the age at which islands typically drown in each hotspot island chain. We found that observed swell subsidence significantly outpaces thermal subsidence. Moreover, island drowning ages match swell residence times, suggesting that islands and the seafloor subside as tectonic plate motion transports them past mantle sources of swell uplift. This correspondence argues strongly for dynamic uplift of the lithosphere at ocean hotspots. Our results also explain global variations in island lifespan on fast- and slow-moving tectonic plates (e.g. drowned islands in the Galápagos <4 million years (Ma) old versus islands >20 Ma above sea level in the Canary Islands), which profoundly influence island topography, biodiversity, and climate.
Statistical modelling of intermittence metrics in temporary rivers of the UK
Authors: Eastman Michael , Parry Simon , Sefton Catherine , Svensson Cecilia
Published: March 2020

Temporary rivers (TRs) are important headwater features of river flow networks, varying dynamically in space and time and providing both terrestrial and freshwater habitats.  In parts of the UK, TRs have become a source of tension between the public and regulators against a backdrop of the competing influences of natural variability, climate change and artificial influences.  Despite this importance, such systems have typically been omitted from monitoring endeavours.  Correspondingly, the occurrence, distribution and characteristics of TRs in the UK are poorly understood.  An enhanced understanding of the features of TRs has the potential to underpin more robust evidence for the protection of aquatic habitats that are vulnerable to drying.

In this study, novel approaches to the statistical modelling of TRs in the UK are adopted to enable the simulation of intermittence metrics. Addressing the challenge of limited observational data, models are trained on data from both the UK and France, drawing on their temporal and spatial advantages, respectively, to maximise their robustness and ability to extrapolate spatially. The performance of a range of statistical modelling and machine learning approaches is evaluated, and applied in simulating intermittence metrics in the UK. 

Preliminary validation results suggest that the modelling approaches are able to replicate observed intermittence metrics where data exist.  Hierarchies of modelling approaches are derived which suggest certain families of models are more effective in simulating flow intermittency in TRs.  The best performing models under validation are taken forward to simulate intermittence patterns beyond networks of observations, helping to identify core regions towards which further focus should be directed by the research and operational TR communities.

Information on the location, prevalence and intermittency of TRs is vital to enhance the efficiency of monitoring strategies with finite resources, and bolster community efforts to engage local stakeholders in gathering additional data.
Ensemble hydrological forecasting for flood warning in small catchments in Saxony, Germany
Authors: Grundmann Jens , Six Achim , Philipp Andy
Published: March 2020

Reliable warnings and forecasts of extreme precipitation and the resulting floods are an important prerequisite for disaster response. Especially for small catchments, warning and forecasting systems are challenging due to the short response time of the catchments and the uncertainties of the meteorological forecast products. Thus, ensemble forecasts of precipitation are an option to portray these inherent uncertainties. By this contribution, we present our operational processing scheme for ensemble hydrological forecasting. We use the COSMO-D2-EPS product of the German Weather Service, which provides an ensemble of 20 members each three hours, for lead times up to 27 hours. Each member is evaluated regarding specific extreme precipitation thresholds for predefined hydrological warning regions. If these thresholds are exceeded in a specific region, rainfall-runoff models for the associated catchments are started to propagate the meteorological uncertainty into the resulting runoff, followed by statistical post processing and visualization. In addition, a communication and training concept based on a series of workshops with the locally responsible civil protection forces to deal with the uncertainties in the forecast is associated. Results are presented by a re-analysis of the flood in the upper Weiße Elster catchment in May 2018 in the Vogtland region of Saxony. Rainfall amounts larger than 140mm in 6 hours led to the highest flood warning levels in the region. Analysis show that such extreme amounts of precipitation are only predicted by one member of the COSMO-D2-EPS ensemble forecast. The deterministic COSMO-D2 model run does not show this, which underlines the benefit and the potential of the ensemble predictions, but also the need for a suitable communication of the uncertainties.
Monitoring and predicting the outstanding 2017 drought in Spain
Authors: Torres Vázquez Miguel Ángel , Halifa Marín Amar , Montávez Juan Pedro , Turco Marco
Published: March 2020

The increase in societal exposure and vulnerability to drought, call to move from post-crisis to pre-impact drought risk management. Accurate and timely information of evolving drought conditions is crucial to take early actions to avoid devastating long-term impacts. A previous study indicated that a statistical empirical method, the ensemble streamflow prediction system (ESP; an ensemble based on reordering historical data), represents a computationally fast alternative to dynamical prediction applications for drought prediction (Turco et al. 2017). Extending this work, here we present an assessment of the ability of the ESP method in predicting the drought of 2017 in Spain considering also the uncertainties coming from the observations. For this, four different datasets are used: that cover a period of 36 years (1981-2017) and with a spatial resolution of 0.25 x 0.25º based on observations of interpolated stations (E-OBS, AEMET), on reanalysis data (ERA5), and on combining stations and satellite data (CHIRPS). Meteorological droughts are defined using the Standardized Precipitation Index aggregated over the months April–September. All the datasets show a similar spatial pattern, with most of the domain suffering extreme drought conditions. In addition, the ESP system achieves reasonable skill in predicting this drought event 2 months in advance with, again, similar pattern among the different datasets. These results suggest the feasibility of the development of an operational early warning system, also considering that the data of CHIRPS and ERA5 are updated every month, i.e., that are available for near-real time applications.

 

References

Turco, M., et al. (2017). Summer drought predictability over Europe: empirical versus dynamical forecasts. Environmental Research Letters, 12(8), 084006.

 

Acknowledgments

The authors acknowledge the ACEX project (CGL2017-87921-R) of the Ministerio de Economía y Competitividad of Spain. AHM thanks his predoctoral contract FPU18/00824 to the Ministerio de Ciencia, Innovación y Universidades of Spain. M.T. has received funding from the Spanish Ministry of Science, Innovation and Universities through the project PREDFIRE (RTI2018-099711-J-I00).
ECCSEL Infrastructure for Isotope Characterization of Reservoirs for Subsurface CO2 Storage
Authors: Johansen Ingar , Huq Farhana , Schöpke Christian Alexander , Yarushina Viktoriya
Published: March 2020

A potential solution to reduce the emission of CO2 in the atmosphere is to store CO2 in subsurface reservoirs. This may be in depleted gas/oil reservoirs, saline aquifers or other porous geological formations, both on shore and off shore. To avoid any hazardous incidents, it is of high importance that the reservoirs can be proven leak free and that there is a good communication within the reservoir.

A useful tool to determine the storage quality of a reservoir is to use Strontium Residual Salt Analyses (Sr-RSA). This is an efficient tool to determine the fluid connectivity of the reservoir and the caprock in horizontal and lateral directions. In addition, it can reveal the presence of barriers and baffles in a geological perspective. Sr-isotope data can also be used to calculate the extent of the barriers and moreover, use of Carbon and Oxygen isotopes measured in cemented barriers can help reveal the history of the barriers (time and temperature of the cementations).

The Geochemistry laboratory at Institute for Energy Technology (IFE) has partially been financed by Horizon 2020 and is a part of the ECCSEL infrastructure. The multi collector (MC)-ICP-MS at IFE’s Geochemical Analysis Lab performs high-precision, high-resolution, and simultaneous measurements of isotope ratios in a wide range of isotope systems. Other Isotopes systems of interest for characterize CO2 storage reservoirs, traditional and non-traditional stable and radiogenic isotopes (Sr, Pb and U, Li, Mg, Ca, Mg, Fe, Cd, Cu, Zn, and Ni), geo- and thermo-chronology, tracing fluid flow patterns, fingerprinting sources of materials, quantifying interactions in biogeochemical systems, and monitoring environmental systems.

By coupling the MC-ICP-MS to IFE’s LA-HR-ICP-MS, the simultaneous analysis of novel isotopes and trace elements in solid materials can be achieved. The laboratory is a state-of-the-art facility for measuring isotope systems to produce data to interpret: biogeochemical reaction rates and products, tracking fluid migration, evaluating fluid/rock interactions and detect CO2 leakage in cap rock.
Untangling the dynamics of the 2019 Ridgecrest sequence by integrated dynamic rupture and Coulomb stress modeling across an immature 3D conjugate fault network
Authors: Gabriel Alice-Agnes , Taufiqurrahman Taufiqurrahman , Carena Sara , Verdecchia Alessandro , Li Bo , Li Duo , Ulrich Thomas , Gallovic Frantisek , Wirp Sara Aniko
Published: March 2020

We present combined 3D dynamic rupture scenarios of the 2019 Mw6.4 Searles Valley and Mw7.1 Ridgecrest earthquakes closely constrained by observations, incorporating complex subsurface material properties, high-resolution topography and off-fault plastic deformation empowered by supercomputing. A detailed 3D non-vertical fault model of the active quasi-orthogonal intersecting fault network is built by integrating relocated aftershocks and surface ruptures constrained by space geodesy and field observations. All faults are exposed to a 3D SCEC community stress model as well as long- and short-term static and dynamic stress transfers, which impact rupture dynamics, particularly in the vicinity of complexities in fault geometry.

By assuming apparently weak faults due to the effect of rapid velocity-weakening friction and elevated fluid pressure, we determine initial stresses and fault strength. Multi-fault rupture directivity and velocity of both events are constrained by aftershock calibrated back-projection. In the presented scenario two conjugate faults simultaneously rupture in the Mw6.4 event, while only the SW-segment breaks the surface. The Mw7.1 event experiences the full final state of stress (dynamic plus static effects) of the Searles Valley scenario, leading to complex rupture including re-activation of the conjugate Mw6.4 segment, mixed crack and pulse-like propagation, tunneling beneath the fault intersection and choosing one Southern branch only. Both events exhibit a high dynamic stress drop reflecting the immature fault system. The foreshock induces a considerable Coulomb stress change in the Mw7.1 hypocentral region; however, not enough to trigger rupture across the stress-shadowed main fault. Both scenarios match key observations including magnitude, rupture speed, directivity, off-fault damage, slip distribution from kinematic inversion, teleseismic waveforms, GPS, and InSAR ground deformation; while shedding light on geometric, strength and stress factors governing the complex rupture evolution and interaction of the Ridgecrest sequence.
Long-term Arctic homogenized radiosondes
Authors: Blaschek Michael , Ambrogi Federico , Haimberger Leopold
Published: March 2020

Radiosonde measurements are potentially valuable indicators of upper air climate change because of their unique long-term availability and their high vertical extent and resolution. The radiosonde network, however, is not a long-term stable measurement system, since it was designed for operational use. Changes in the observation system are frequent and surf the purpose of competitive daily weather prediction, but result in more or less clear breakpoints in the observed long-term time series. These artificial biases need to be removed. We apply a bias adjustment scheme for radiosonde temperatures and humidity based on departures from a recent reanalysis, ERA5 potentially back to 1950. Newly digitized and recovered radiosonde data have been used within ERA5 for the first time. We present long-term bias adjustments and trends as preliminary results. In particular, we focus on the water vapour transport into the Arctic as a result of polar amplification and meridional heat exchange.
The analytical model of McCartney applied in the eastern Levantine basin: formation of the Cyprus eddy and associated sub-basin and mesoscale features
Authors: Pirro Annunziata , Gerin Riccardo , Mauri Elena , Hayes Dan , Poulain Pierre-Marie
Published: March 2020

The circulation in the Levantine Eastern Mediterranean basin is characterized by a complex system of sub-basin and mesoscale features. The most predominant and persistent eddy is an anticyclonic feature located south of Cyprus and identified as the Cyprus Eddy (CE). Previous studies based on in-situ data, satellite and model outputs confirm the presence of this warm core eddy centered around 33°E, 33.5°N. Although the center of the CE might be found slightly shifted to the west /east for different years of analysis, the anticyclonic eddy appears always above the Eratosthenes seamount whose peak lies at the depth of ~ 690 m and it rises ~ 2500 m above the surrounding seafloor. The presence of a cyclonic and anticyclonic eddy named South Shikmona (SSE) and North Shikmona (NSE) eddy, respectively has been also detected east of the CE and west of the Lebanese and Israeli coasts. Here, we present a hypothesis that attempts to explain the formation mechanism of the three eddies described above. Specifically, for an eastward stratified current on a b plane, the isolated seamount forces a Taylor column above it which can be identified as the CE. A standing wake downstream is also formed, and embedded eddies are associated with the SSE and NSE. These sub-basin features are probably part of a Rossby wave system. The analytical model of McCartney 1976 supports this hypothesis. Reanalysis and sea glider data collected during the CINEL project sponsored by the U.S. Office of Naval Research (ONR) are used to investigate McCartney’s solution. Preliminary results confirm the presence of a series of eddies above and downstream the sea mountain supporting therefore, the advanced hypothesis.