bluuebunny/crossref_metadata_2025 huggingface dataset:
Combined integrated hydrological modeling and particle tracking algorithms to infer the temporal variability of transit and residence time distributions within the Strengbach catchment (Vosges mountains, France)
Authors: Weill Sylvain , Lesparre Nolwenn , Jeannot Benjamin , Delay Frederick
Published: March 2020

The temporal variability of transit-time distributions (TTDs) and residence-time distributions (RTDs) in hydrological systems has received particular attention recently because of their ability to inform on elementary processes impacting geochemical signatures and water fluxes in ecosystems. To date, these distributions and their temporal variability have been mainly investigated through concentration measurements of conservative geochemical or isotopic tracers. Even though physically-based and distributed hydrological models can render interpretations of TTDs/RTDs in terms of processes and physical controls, the variability of TTDs and RTDs has barely been studied using distributed hydrological modeling. In this study, an integrated hydrological model has been coupled with particle tracking algorithms and applied to the Strengbach Catchment – a small mountainous catchment belonging to the French network of critical zone observatories – to investigate the eventual link between water storage in the catchment and the temporal variability of TTDs and RTDs. The model calibration is performed relying upon both classical streamflow measurements and magnetic resonance sounding, a geophysical measure sensible to the water content in the subsurface. The model is then run over a 10-year period for which time distributions are calculated at various deadlines. The results show that the response of the Strengbach catchment is uncommon with short mean transit times (approximately 150-200 days) and a weak variability of TTDs and RTDs with the water storage. This specific behavior is mainly linked to the small size of the system and specific climatic and topographic conditions. Because the hydrological model was calibrated on the basis of unusual data (local water contents inferred via MRS measurements), ongoing investigations target the evaluation of the sensitivity of transit time distributions with respect to uncertainties plaguing calibrating data.
Assessment of the effects of non-aqueous phase liquid (NAPL) pollution on aquatic macroinvertebrates survivorship
Authors: Anuradha Anuradha , Wood Paul , Das Diganta , Yadav Brijesh
Published: March 2020

Massive production, extensive use and poor disposal practices of organic chemicals from industries and fuel facilities have polluted soil and water resources. Non-aqueous phase liquids (NAPLs), including oils and fuel hydrocarbons are immiscible in water, moving as separate layers based on their density. Due to their high persistence, they are seldom flushed from the system, potentially making it unfit for use later. Along with resource consumption, pollution also poses a threat to dependent aquatic life. NAPLs have the potential to disturb the physiological, behavioral and breeding performance of aquatic organisms, by affecting their oxygen and nutrient uptake from the system. To analyze these effects, this study examined the response of two common European freshwater macroinvertebrates: Gammarus pulex (freshwater shrimp) and Baetis rhodani (mayfly larvae) to controlled exposure of mineral oil (a representative NAPL). The experiments were conducted in the laboratory for a 24-hour period to observe any changes in their locomotion and survivorship at different concentrations of mineral oil. Results indicate that mineral oil has a serious effect on the organism’s movement and survivorship. Gammarus pulex displayed a high tolerance compared to the mayfly (Baetis rhodani). Most mayfly larvae died due to NAPL exposure. The results indicate that both organisms respond rapidly to NAPL contamination, providing the potential for the development of bio-monitoring tools for water quality studies.

Keywords: Aquatic macroinvertebrates, NAPLs, pollution, response
Coupling of sea level changes and neotectonic activities in the Pearl River Delta─insight from stratigraphic profile and chronology
Authors: Huang Ping , Liang Hao
Published: March 2020

        Despite several tens of Pleistocene eustatic oscillations, it is surprised that only two marine sequences were preserved in the PRD (Pearl River Delta), the third biggest delta along the mainland China coast. The younger marine sequence (SQ1) has been consensus on the age of Holocene, i.e., MIS1, whereas the chronology of the older marine sequence (SQ2) is still in debate, i.e. belongs to MIS3 or MIS5. Those favor younger transgression suggest rapid uplift following the SQ2 deposited according to 14C and early luminescence dating, while the others argued that the current depth of SQ2 is affected by tectonic subsidence and better match the sea-level altitude in MIS5. To address this problem, it is significant to investigate a complete spatial distribution of SQ2 prior to dating. We applied 250 boreholes to acquire 5 Quaternary stratigraphic profiles throughout the PRD. These profiles reveal that the deposition area of SQ2 with current depth at -15 - -35m a.s.l. only reach the southern part of PRD, showing a much less area than SQ1. Sediments synchronous to SQ2 in the northern part of PRD present coarse grain in fluvial or piedmont environment, implying an erosional state. Preliminary OSL dating on SQ2 in boreholes in southern PRD yielded 85.5±5 ka, suggesting the SQ2 probably deposited in MIS5, here we infer to the high sea-level in MIS5a with altitude at ca. -20m. Moreover, we estimate the isostasy by erosion of granite highland in/around the PRD via hypsometric integral curve. We find that the modern average altitude of the highland is ca. 100-150m lower than the estimated isostatic altitude, suggesting tectonic subsidence in PRD. Overall, we interpret that the PRD was an eroding highland and keep subsiding since MIS5. Because of the topographic high, transgression occurred in MIS5 did not extend northward to modern delta area and led to absence of SQ2 in northern PRD. Subjected to tectonic subsidence, the once topographic high subsided beneath the modern sea-level but still higher the sea-level in MIS3. Marine sequence did not develop in PRD until transgression occurred in Holocene.
Ocean Response to Successive Typhoons Sarika and Haima (2016) in the Northern South China Sea
Authors: Zhang Han
Published: March 2020

Tropical cyclones (TCs) are natural disasters for coastal regions. TCs with maximum wind speeds higher than 32.7 m/s in the north-western Pacific are referred to as typhoons. Typhoons Sarika and Haima successively passed our moored observation array in the northern South China Sea in 2016. Based on the satellite data, the winds (clouds and rainfall) biased to the right (left) sides of the typhoon tracks. Sarika and Haima cooled the sea surface ~4 and ~2 °C and increased the salinity ~1.2 and ~0.6 psu, respectively. The maximum sea surface cooling occurred nearly one day after the two typhoons. Station 2 (S2) was on left side of Sarika’s track and right side of Haima’s track, which is studied because its data was complete. Strong near-inertial currents from the ocean surface toward the bottom were generated at S2, with a maximum mixed-layer speed of ~80 cm/s. The current spectrum also shows weak signal at twice the inertial frequency (2f). Sarika deepened the mixed layer, cooled the sea surface, but warmed the subsurface by ~1 °C. Haima subsequently pushed the subsurface warming anomaly into deeper ocean, causing a temperature increase of ~1.8 °C therein. Sarika and Haima successively increased the heat content anomaly upper than 160 m at S2 to ~50 and ~100 m°C, respectively. Model simulation of the two typhoons shows that mixing and horizontal advection caused surface ocean cooling, mixing and downwelling caused subsurface warming, while downwelling warmed the deeper ocean. It indicates that Sarika and Haima sequentially modulated warm water into deeper ocean and influenced internal ocean heat budget. Upper ocean salinity response was similar to temperature, except that rainfall refreshed sea surface and caused a successive salinity decrease of ~0.03 and ~0.1 psu during the two typhoons, changing  the positive subsurface salinity anomaly to negative.
Composite data set of last glacial Dansgaard/Oeschger events obtained from stable oxygen isotopes in speleothems
Authors: Fohlmeister Jens , Bores Niklas , Marwan Norbert , Columbu Andrea , Rehfeld Kira , Sekhon Natasha , Sime Louise , Veiga-Pires Cristina
Published: March 2020

Millennial scale climate variations called Dansgaard-Oeschger cycles occurred frequently during the last glacial, with their central impact on climate in the North Atlantic region. These events are, for example, well captured by the stable oxygen isotope composition in continental ice from Greenland, but also in records from other regions. Recently, it has been shown that a water isotope enabled general circulation model is able to reproduce those millennial-scale oxygen isotope changes from Greenland (Sime et al., 2019). On a global scale, this isotope-enabled model has not been tested in its performance, as stable oxygen isotope records covering those millennial scale variability were so far missing or not systematically compiled.

In the continental realm, speleothems provide an excellent archive to store the oxygen isotope composition in precipitation during those rapid events. Here, we use a newly established speleothem data base (SISAL, Atsawawaranunt et al., 2018) from which we extracted 126 speleothems, growing in some interval during the last glacial period. We established an automated method for identification of the rapid onsets of interstadials. While the applied method seems to be not sensitive enough to capture all warming events due to the diverse characteristics of speleothem data (temporal resolution, growth stops and dating uncertainties) and low signal-to-noise-ratio, we are confident that our method is not detecting variations in stable oxygen isotopes that do not reflect stadial-interstadial transitions. Finally, all found transitions were stacked for individual speleothem records in order to provide a mean stadial-interstadial transition for various continental locations. This data set could be useful for future comparison of isotope enabled model simulations and corresponding observations, and to test their ability in modelling millennial scale variability.

 

References

Atsawawaranunt, et al. (2018). The SISAL database: A global resource to document oxygen and carbon isotope records from speleothems. Earth System Science Data 10, 1687–1713

Sime, L. C., Hopcroft, P. O., Rhodes, R. H. (2019). Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period. PNAS 116, 4099-4104.
Sentinel 5 Precursor: Status of TROPOMI and the Operational Data Products
Authors: Veefkind Pepijn , Aben Ilse , Dehn Angelika , Kleipool Quintus , Loyola Diego , Richter Andreas , van Roozendael Michel , Siddans Richard , Wagner Thomas , Zehner Claus , Level Pieternel
Published: March 2020

The Copernicus Sentinel 5 Precursor (S5P) is the first of the Sentinel satellites dedicated to the observation of the atmospheric composition, for climate, air quality and ozone monitoring applications. The payload of S5P is TROPOMI (TROPOspheric Monitoring Instrument), a spectrometer covering spectral bands in ultraviolet, visible, near infrared and shortwave infrared, which was developed by The Netherlands in cooperation with the European Space Agency (ESA). TROPOMI has a wide swath of 2600 km, enabling daily global coverage, in combination with a high spatial resolution of about 3.5 x 5.5 km2 (7 x 5.5 km2 for the SWIR band).

S5P was successfully launched on 13 October 2017 and following a six-month commissioning phase, the operational data stream started at the end of April 2018. All of the TROPOMI operational data products have been released, with the exception of the ozone profile, which is planned to become available with the next major release[AR1]  of the Level 1B data. In addition to the operational data products, new research products are also being developed.

In this contribution, the status of TROPOMI and its data products will be presented. Results for observations of recent events will be provided, along with an outlook on the next release of the data products.

 
Achieving Net Zero: Understanding the Potential Hydrological Impacts of Changing Climate and Land Cover in the UK
Authors: Buechel Marcus , Dadson Simon , Slater Louise
Published: March 2020

Climate change is set to increase the magnitude and frequency of fluvial flooding in many regions across the world, making it a growing risk to billions of people living near rivers. Changing drainage basin land cover and hydrological connectivity further complicates how these streamflow extremes may evolve. Engineered solutions to mitigate the risk of future high magnitude runoff events to populations may no longer be suitable to meet these needs due to these changes in climate and land cover.

By reducing the level of global CO2 emissions, climate models predict that we can reduce the severity of climate change impacts upon communities. To achieve the goals set by the Paris Agreement to limit global warming, the UK has proposed a range of policies to reach net zero carbon emissions by 2050. One of these proposals includes widespread afforestation across the UK. Where to plant this woodland and the scale of impact it may have on the future hydrological cycle is currently unquantified. This project seeks to investigate three aspects of how future streamflow trends my change due to afforestation in respect to: woodland location, differing afforestation rates, and the hydrological responsiveness of drainage basins to land cover changes.

Physics-based models provide the possibility to explore the relative importance of climate and land cover on future streamflow trends, both together and separately. The Joint UK Land Environment Simulator (JULES) is used to explore catchment responses across the UK to potential extreme weather events with theoretical changes in land cover at a 1 km resolution. Theoretical land cover scenarios of afforestation were generated according to proximity to existing land cover, drainage basin structure and proposed afforestation sites. An extreme precipitation scenario (the winter of 2013/14) is explored to comprehend streamflow regime response to high magnitude precipitation events caused by changing climate and land cover using the Weather@home perturbed model ensembles and CHESS-met datasets. This approach provides the potential to explore how increasing afforestation could change the discharge dynamics of landscapes across the UK and thus its potential benefits and drawbacks to flood risk management. 

Results show how potential land cover changes will impact streamflow response to storms across the UK. These results help provide a clearer picture of how changing landscape systems impact river response to external climatic forcing and may provide evidence for management and policy strategies tailored to the requirements of individual drainage basins to reduce the risk of flooding upon downstream populations.
Predicting the magnetic flux rope fields at the Sun-Earth L1 point
Authors: Amerstorfer Ute , Möstl Christian , Bailey Rachel , Weiss Andreas , Reiss Martin , Amerstorfer Tanja , Hinterreiter Jürgen , Bauer Maike
Published: March 2020

Forecasting of coronal mass ejection magnetic flux rope fields at L1 is a long-standing challenge and one of the major problems in space weather forecasting. We attempt to make progress by using two approaches: 1) machine learning approaches (e.g., linear regression, lars lasso, RANSAC, or random forest), and 2) analogue ensemble methods. For our study, we take events observed at the Wind, Stereo-A and Stereo-B satellites from the ICME list created within the EU-project HELCATS. We analyse different scores (e.g., RMSE, or the skill of the model) of the presented methods. Further, we investigate how well the flux rope field can be anticipated when the first few hours of the flux rope have already been observed at L1.
Reconstructing root system architectures from non-invasive imaging techniques for the use in functional structural root models
Authors: Landl Magdalena , Huber Katrin , Pohlmeier Andreas , Vanderborght Jan , Pflugfelder Daniel , Roose Tiina , Schnepf Andrea
Published: March 2020

The combination of functional-structural root-system models with root architectures derived from non-invasive imaging is a promising approach for gaining a better understanding of root-soil interaction processes. However, root architectures can often not be fully recovered using imaging, which subsequently affects the assessment of function via the functional-structural root models. In this study, we explored theoretical and actual possibilities of root system reconstruction from MRI and X-ray CT images. Experiments with water-filled capillaries showed the same minimum detectable diameter for both MRI and X-ray CT for the used parameter setup. Experiments with soil-grown lupine roots, however, showed significantly lower root system recovery fractions for MRI than for X-ray CT, from which most roots thicker than 0.2 mm could be recovered. MRI allowed root signal detection below voxel resolution; however, the connection of this signal to a continuous root structure proved difficult for large, crowded root systems. Furthermore, soil moisture levels >30% hampered root system recovery from MRI scans in experiments with pure sand. To overcome the problem of low root system recovery fractions, we developed a new method that uses incomplete root systems as a scaffold onto which missing roots are simulated using information from WinRhizo measurements. Comparisons of root length within subsamples of semi-virtual root systems and root systems derived from X-ray CT scans showed good agreement. Evaluation of hydraulic root architecture measures of incomplete root system scaffolds and semi-virtual root systems proved the importance of using complete root system reconstructions to simulate root water uptake. Semi-virtual root reconstruction thus appears to be a promising technique to complete root systems for subsequent use in functional-structural root models.
Transformation of the first mode internal solitary wave over topography in three-layer flow
Authors: Terletska Kateryna , Talipova Tatiana , Grimshaw Roger , Liu Zihua , Maderіch Vladimir
Published: March 2020

Transformation of the first mode internal solitary wave over the underwater bottom step in three-layer fluid is studied numerically. In the three layer flow two modes (the first and the second) of the internal waves are existed. It is known that interaction of the first mode internal solitary wave with an underwater obstacle is the mechanisms of second-mode internal solitary waves generation. Different scenarios of transformation are realized under different wave characteristics: wave amplitude, position of the step and thickness of the layers as is the two layer case [1]. Formation of the second mode internal solitary waves during interaction of the first mode internal solitary waves occurs only for special range of wave characteristics and thickness of the layers that was defined in this investigation. The second mode internal solitary waves appear as in the reflected wave field as well as in the transmitted wave field. Transfer of energy from incident mode one wave into reflected and transmitted waves (the first and the second modes) during transformation is also studied. Dependence of the amplitudes of generated solitary waves (transmitted and reflected) from amplitude of the incident wave is obtained.  Comparison of numerical results (reflected and transmitted coefficients) with the theoretical calculations [2] shows good agreement in the range of wave characteristics that corresponds to the weak interaction.  

 

1. Talipova T., Terletska K., Maderich V., Brovchenko I., Pelinovsky E., Jung K.T., Grimshaw R. Internal solitary wave transformation over a bottom step: loss of energy. Phys. Fluids. 2013. № 25. 032110; doi:10.1063/1.4797455

2.    Liu Z., Grimshaw R. and Johnson E.  The interaction of a mode-1 internal solitary wave with a step and the generation of mode-2 waves Geophysical & Astrophysical Fluid Dynamics 2019, N 4, V 113, https://doi.org/10.1080/03091929.2019.1636046

 
The Atlantic Water boundary current North of Svalbard in 2018-2019: background properties, dynamics and turbulence.
Authors: Koenig Zoé , Kolås Eivind , Kalhagen Kjersti , Fer Ilker
Published: March 2020

North of Svalbard is a key region for the Arctic Ocean heat and salt budget as it is the gateway for one of the main branches of Atlantic Water in the Arctic. As the Atlantic Water layer advances into the Arctic Ocean, its core deepens from about 250 m depth around the Yermak Plateau to 350 m in the Laptev Sea, and gets colder and less saline due to mixing with surrounding waters. The complex topography in the region facilitates vertical and horizontal exchanges between the water masses and, together with strong shear and tidal forcing driving increased mixing rates, impacts the heat and salt content of the Atlantic Water layer that will circulate the Arctic Ocean.

In summer 2018, 6 moorings organized in 2 arrays were deployed across the Atlantic Water Boundary current for a year, within the framework of the Nansen Legacy project. In parallel, turbulence structure in the Atlantic Water boundary current was measured north of Svalbard in two different periods (July and September), using a Vertical Microstructure Profiler (Rockland Scientific) in both cruises and a Microrider (Rockland Scientific) mounted on a Slocum glider in September.

Using mooring observations, we investigated the background properties of the Atlantic Water boundary current (transport, vertical structure, seasonal variations) and the possible sources of the low-frequency variations (period of more than 2 weeks).

 Using observations during the cruise periods, we investigated changes in the mixed layer through the summer and the sources of vertical mixing in the water column. In the mixed layer, depth-integrated turbulent dissipation rate is about 10-4 W m-2. Variations in the turbulent heat, salinity and buoyancy fluxes are strong, and hypothesized to be affected by the evolution of the surface meltwater layer through summer. When integrated over the Atlantic Water layer, the turbulent dissipation rate is about 3.10-3 W m-2. Whilst the wind work exerted in the mixed layer accounts for most of the variability in the mixed layer, tidal forcing plays an important role in setting the dissipation rates deeper in the water column.
Meteorological Parameters of Thunderstorm Ground Enhancements
Authors: Svechnikova Ekaterina , Ilin Nikolay , Mareev Evgeny
Published: March 2020

Thunderstorm ground enhancements (TGEs) are events of energetic particle flux increases, discovered and observed at the Aragats Research Station (Armenia). Energetic particles are accelerated and multiplied in the electric field of clouds, and may be registered by ground-based detectors. Analysis of the structure of thunderclouds producing TGEs is crucial for clarifying the mechanism of particle acceleration.

In the present study the hydrometeor dynamics are analysed on the basis of the state of the atmosphere modeling by means of Weather Research and Forecasting Model. Meteorological characteristics typical of TGE occurrence in the mountainous region of Aragats are discovered. A technique has been developed for estimation of the charge distribution in a cloud on the basis of comparison of the simulations and experimental data. The retrieved cloud electrical structure is used to estimate the dependence of the electrification process on the temperature and liquid water content.

An unusually low concentration of ice particles leads to the great importance of snow particles in the process of charge separation. A typical charge distribution in a TGE-producing cloud is found to be well approximated by a two-layered charge structure with a lower positive charge region formed by graupel particles and an upper negative region formed by snow particles. Characteristic charge density is 0.01 C/km^3 for graupel cluster and 0.02 C/km^3 for snow cluster. A vertical distance of about 1-2 km between the lower positive and upper negative layers is sufficient for the development of an energetic particle avalanche.

The obtained estimation of the hydrometeor content and the electrical structure of a TGE-producing cloud provides new evidence on particle acceleration mechanisms in the atmosphere and processes of charge distribution in mountainous conditions.
Extremely fast retrieval of volcanic SO2 layer heights from UV satellite data using inverse learning machines
Authors: Hedelt Pascal , Koukouli MariLiza , Taylor Isabelle , Balis Dimitris , Grainger Don , Efremenko Dmitry , Loyola Diego
Published: March 2020

Precise knowledge of the location and height of the volcanic sulfur dioxide (SO2) plume is essential for accurate determination of SO2 emitted by volcanic eruptions. So far, UV based SO2 plume height retrieval algorithms are very time-consuming and therefore not suitable for near-real-time applications like aviation control. We have therefore developed the Full-Physics Inverse Learning Machine (FP_ILM) algorithm for extremely fast and accurate retrieval of volcanic SO2 layer heights based on the UV satellite instruments Sentinel-5 Precursor/TROPOMI and MetOp/GOME-2.

In this presentation, we will present the FP-ILM algorithm and show results of the 2019 Raikoke eruption; a strong volcanic eruption which has emitted a huge ash cloud accompanied by more than 1300 DU of SO2, which could be detected  even two months after the end of eruptive event. We will also present first results of the recent Taal volcanic eruption on 13 January 2020 in Indonesia, which has injected a huge ash and SO2 plume into the upper atmosphere, with plume heights of up to 20km. 

The algorithm is developed in the framework of ESA's  "Sentinel-5p+ Innovation: SO2 Layer Height project" (S5P+I: SO2 LH),  dedicated to the generation of an SO2 LH product and its extensive verification with collocated ground- and space-born measurements.

The high-resolution UV spectrometer GOME-2 aboard the three EPS MetOp-A, -B, and –C satellites perform global daily atmospheric trace-gas measurements with a spatial resolution of  40x40km2 at an overpass time of 8:30h local time. The UV spectrometer TROPOMI aboard the ESA Sentinel-5P satellite provides a much higher spatial resolution of currently 5.6x3.6km2 per ground pixel, at an overpass time of 13:30h. In the future, also UV instruments aboard the Sentinel-4 (geostationary) and Sentinel-5 will complement the satellite-based global monitoring of atmospheric trace gases.
MAX-DOAS NO2 profile retrieval over Minsk: 3 years of observation
Authors: Bruchkouski Ilya , Barodka Siarhei , Wang Yang
Published: March 2020

For NO2 monitoring by MAX-DOAS method, the automated instrument MARS-B based on the spectrograph ORIEL MS257 with a Peltier-cooled CCD-array detector Andor Technology DV-420 OE (number of active pixels is 1024×256, working temperature is -40 ºC) has been employed. The MARS-B instrument records the spectra of scattered sunlight in the range of elevation angles 0º – 90º within vertical angle aperture of 1.3º in spectral range 340-400 nm with FWHM = 0.32 nm and is operating without mechanical shutter. Radiation input system is working without optical ï¬ber and spectrograph unit has open-air design, spectrograph unit is temperature-stabilized at level 40 ± 0.5 ºC. The MARS-B instrument successfully took part in MAD-CAT (2013) and CINDI-2 (2016) international inter-comparison campaigns.

Since 2017 MARS-B instrument is performing spectra registering over Minsk (National Ozone Monitoring Research and Education Centre, Minsk, Belarus) using multi-axis geometry of observations during daytime and zenith geometry in twilights. More than 4.5 millions of day-time spectra aiming to retrieve differential slant columns of ozone, nitrogen dioxide and oxygen dimer have been processed by DOAS method. Total nitrogen dioxide columns have been retrieved by PriAM algorithm which is based on optimal estimation method.

Continuous 3-year MAX-DOAS measurements (nitrogen dioxide vertical column, near-surface nitrogen dioxide concentrations, aerosol optical depth) over Minsk in period of 2017 - 2019 will be presented, compared with data of impact gas analyzers and satellite data, analyzed and discussed. Also, zenith twilights measurements will be processed aiming to retrieve stratospheric nitrogen dioxide and ozone columns for comparison with different parameters of solar activity.
Regional modeling of urban climate: the impact of physical process representation
Authors: Huszár Peter , Karlický Jan , Ďoubalová jana , Nováková Tereza , Švábik Filip , Belda Michal , Halenka Tomáš
Published: March 2020

The urban heat island (UHI) is a relaively old concept and has been widely studied using both observational and modeling approches. However, urban canopies impact the meteorological conditions in the planetary boundary layer (PBL) and above in many other ways, e.g. urban breeze circulation can form, enhanced drag causes intensification of the turbulent diffusion leading to elevated PBL height, reduced evaporation results in decreased absolute humidity, changes in cloudiness etc.
A well established regional model representation of these phenomena is crucial for both mitigation and adaptation in areas affected by intense urbanization and climate change. There are however large uncertainities how the underlying physical processes are represented in numerical models, i.e. what models are used along with which parameterizations and parameters.

Here we perform a regional multi-model analysis over central Europe using the Regional Climate Model (RegCM4) and Weather Research and Forecast (WRF) regional models with different configurations representing different PBL treatment, convection parameterization, surface layer physics, microphysics and urban canopy models. Model results are extensively compared to surface measurements as well as satellite observation of surface temperatures. We analyse the model results mainly in terms of the urban-rural contrast which is a measure of the difference between the urban core value and the vicitinity (with respect to the particular city) for selected meteorological parameters. Our results show substantial impact of the choice of the model as well as the choice of parameterization on the intensity of UHI and other meteorological effects. The urban-rural difference of PBL height and average wind speed between urban areas and their vicinity is affected the most, controlled by the boundary layer physics parameterization.
Our simulations confirm the large uncertainity in how models resolve the meteorological features specific to urbanized areas and this has to be taken into account when designing different strategies for urban planning and multimodel approaches should be preferred.
The Copernicus atmospheric Mission Sentinel-4: Status of algorithm developments for the L1b and L2 processors
Authors: Bazalgette Courrèges-Lacoste Grégory , Wright Norrie , Veihelmann Ben , Ahlers Berit , Le Rille Olivier , Gimeno Garcia Sebastian , Dobber Marcel
Published: March 2020

The Copernicus missions Sentinel-4 (S4) and Sentinel-5 (S5) will carry out atmospheric composition observations on an operational long-term basis to serve the needs of the Copernicus Atmosphere Monitoring Service (CAMS) and the Copernicus Climate Change Service (C3S).

Building on the heritage from instruments such as GOME, SCIAMACHY, GOME-2, and OMI, S4 is an imaging spectrometer instruments covering wide spectral bands in the ultraviolet and visible wavelength range (305-500nm) and near infrared wavelength range (750-775 nm). S4 will observe key air quality parameters with a pronounced temporal variability by measuring NO2, O3, SO2, HCHO, CHOCHO, and aerosols over Europe with an hourly revisit time.

A series of two S4 instruments will be embarked on the geostationary Meteosat Third Generation-Sounder (MTG-S) satellites. S4 establishes the European component of a constellation of geostationary instruments with a strong air quality focus, together with the NASA mission TEMPO and the Korean mission GEMS.

This paper will address the development status of the L1b Operational Processor (L1OPS) by EUMETSAT and the supporting L1b reference processor (L1RP) developed by ESA; In dedicated cases (e.g. CTI, Non-linearity signal loss, ...) the algorithms input from the S4 Industrial Prime have been used. The paper will also provide an overview of the status of the Level 2 processor developed by ESA for integration into the EUMETSAT MTG-S ground segment.
A 12-month UK air quality aircraft campaign and model evaluation
Authors: Smith Eleanor R. , Mynard Angela , McInnes Rachel N. , Hort Matthew C. , Agnew Paul , Kent Joss , Wilson Andy , Tiddeman David , Bowles James , Langridge Justin M. , Wivell Kirsty , Szpek Kate , Barrett Paul A. , King Robert , Archibald Alexander T.
Published: March 2020

Surface concentrations of pollutants in the UK are generally well observed and column averaged data is increasingly available from satellites. However, there remains limited data on the vertical distribution of key pollutants in the UK boundary layer.

As part of the Strategic Priorities Fund Clean Air programme, the Met Office Civil Contingencies Aircraft (MOCCA) has been instrumented to enable measurements of ozone, nitrogen dioxide, sulphur dioxide and particulate matter (PM2.5 and PM10) to be made in the UK boundary layer.

These ongoing observations are being used to evaluate Air Quality in the Unified Model (AQUM), improve air quality forecasts and hence ultimately improve our confidence in the model data used to perform assessments of the health impacts of pollution in the UK.

Here we present our methodology, initial investigation of model and aircraft data from flights during the first 6 months of the project and future plans for this work.
Discrimination between earthquakes and quarry blasts in the Vertes Hills, Hungary using a correlation detector
Authors: Kiszely Márta , Bálint Süle , Bondár István
Published: March 2020

Contamination of earthquake catalogues with anthropogenic events largely complicates seismotectonic interpretation. It is especially true for relatively low seismicity areas, such as Hungary. In the present study, we analyze the characteristics of the waveforms of earthquakes and quarry blasts that occurred in the close vicinity of Csokako (CSKK) station between 2017 and 2019 in the Vértes Hills, Hungary.

The objective of this study was to determine the linear discrimination line between the of earthquake and explosion populations. We investigated the effectiveness of P/S amplitude ratios using filtered waveforms at different frequency bands. We applied waveform cross-correlation to build correlation matrices at CSKK and performed hierarchical cluster analysis to identify event clusters. Because most of the quarry blasts were carried out by ripple-fire technology, we computed spectrograms and examined the spectral ratio between low and high frequencies and the steepness of spectra.

Overall, classes of earthquakes and quarry blasts have separated well from each other by combining the amplitude ratio, waveform similarity and the different spectral methods. We created a set of master events for individual quarries to run correlation detectors on past waveforms and identify the explosions of analyzed quarries that were misclassified as earthquakes in the annual Hungarian National Seismological Bulletins.
Abundance of plastic debris across European and Asian rivers
Authors: van Calcar Caroline , van Emmerik Tim
Published: March 2020

Plastic pollution in the marine environment is an urgent global environmental challenge. Land-based plastics, emitted into the ocean through rivers, are believed to be the main source of marine plastic litter. According to the latest model-based estimates, most riverine plastics are emitted in Asia. However, the exact amount of global riverine plastic emission remains uncertain due to a severe lack of observation. Field-based studies are rare in numbers, focused on rivers in Europe and North America and used strongly varying data collection methods. We present a harmonized assessment of floating macroplastic transport from observations at 24 locations in rivers in seven countries in Europe and Asia. Visual counting and debris sampling were used to assess (1) magnitude of plastic transport, (2) the spatial distribution across the river width, and (3) the plastic polymer composition. Several waterways in Indonesia and Vietnam contain up to four orders of magnitude more plastic than waterways in Italy, France, and The Netherlands in terms of plastic items per hour. We present a first transcontinental overview of plastic transport, providing observational evidence that, for the sampled rivers, Asian rivers transport considerably more plastics towards the ocean. New insights are presented in the magnitude, composition, and spatiotemporal variation of riverine plastic debris. We emphasize the urgent need for more long-term monitoring efforts. Accurate data on riverine plastic debris are extremely important to improve global and local modeling approaches and to optimize prevention and collection strategies.
Determination of "Double Control" Management Threshold Value for Groundwater Based on GMS -- A Case Study of Changchun City, Jilin Province
Authors: Qi Linlin , Zhang Xiaoying , Dai Zhenxue , Jia Sida , Ma Funing
Published: March 2020

Determination of "Double Control" Management Threshold Value for Groundwater Based on GMS -- A Case Study of Changchun City, Jilin Province

Linlin Qi1, Xiaoying Zhang1, Zhenxue Dai1, Sida Jia 1, Funing Ma 1

（1. College of Construction Engineering, Jilin university, Changchun 130021, China）

Groundwater is an essential controlling factor for economic and social development, human survival and good ecological environment. Many areas use groundwater as a regular source of water. However, with the development of economy and society, water pollution problems keep emerging, water resources crisis is increasingly serious, especially in the northern water resources shortage areas, so groundwater management is particularly important. It is no longer possible to objectively reflect the groundwater safety situation in a certain area by controlling the amount of groundwater mining or the groundwater level. Therefore, it is necessary to construct the groundwater “dual-control” management mode. However, the foundation of “dual-control” management is to establish the mathematical relationship between the groundwater control level and the amount of groundwater mining. Taking Changchun city in Jilin province as an example, the study area was divided into different management zones, and the threshold value about the groundwater level and the amount of groundwater mining were determined by analytical method. Then using GMS software to establish a model of groundwater resources in the study area. After identification authentication model to simulate the groundwater resources and the relationship between the groundwater table, ultimately determine the threshold value of groundwater level and water quantity under dual control management in this area. It can be used as the most intuitive data of groundwater dual control management and control. With the groundwater protection as the starting point and the sustainable utilization of resources as the goal, it will be the focus of future research in China to establish the groundwater management mode of "water level" and "water quantity", in order to make the groundwater management more flexible, controllable and scientific.
Quantitative estimation of genetic components in the seasonal runoff of a small river by the graphoanalytic and isotopic method
Authors: Chizhova Julia , Kireeva Maria , Tebenkova Natalia , Kositsky Alexey
Published: March 2020

The processes of spring flood formation associated with intensive snow melting are becoming less and less predictable, and forecasts of such important characteristics as maximum discharge and water level do not fit into the allowable ranges of error. In some areas, a sharp decrease in river runoff was observed, followed by catastrophic floods, associated with the anomalous hydrometeorological conditions and an unfavorable combination of flow-forming factors. All this testifies to the change in runoff formation processes in regions with a significant share of snow-fed rivers. A new method of storing processing and visualizing of the information is developed to bridge the gap between point data on river runoff and globally distributed data on characteristics affecting the genetic components of runoff. The use of new model for separating runoff into genetic components was verified by isotope hydrograph separation.

Under unsteady climate conditions, the isotope signature of river water within a year and on a multi-year scale is an important indicator of the response of hydrological system to change (associated with different amounts of snow in the winter and different contributions of snow melting to the river and groundwater reservoir). Observations at the local site of the Protva River catchment on the European Plain showed that over 9 years (in 2009-2010 and in 2019), the groundwater component did not change its isotopic characteristics: δ18О = -12.3 ‰. The intra- and interannual fluctuations associated with different amounts of atmospheric precipitation entering the upper groundwater horizon practically did not shift oxygen isotope composition of water. In 2014, the weighted average annual value δ18О of the precipitation for Moscow was -12.1‰ (Chizhova et al., 2017). The δ18О value of precipitation in the summer months varies from -3 to -10 ‰. In Protva river runoff in mid-summer the contribution of precipitation is from 16 to 34% according to the isotope hydrograph separation. This work was supported by RSF project 19-77-10032.
Water quality impacts from tidal flooding in the northeast coast of the U.S.
Authors: Macias-Tapia Alfonso , Mulholland Margaret , Loftis Derek , Selden Corday , Bernhardt Peter
Published: March 2020

Little is known about the chemical and biological effects of tidal flooding on adjacent aquatic environments. Terrestrial systems accumulate various types of organic and inorganic matter that can be dissolved or carried into adjacent water bodies as floodwaters recede. In the northeast coast of the United States, the incidence and duration of coastal flooding has increased due to the high relative rates of sea level rise in the region.  Much of this flooding is tidal, occurring in the absence of rainfall during spring tides and/or when wind-induced Ekman transport is onshore.  While there are estimates of stormwater inputs into coastal systems, material (e.g., sediment, nutrients and contaminating bacteria) transported into the water bodies as tidal floodwaters recede have not been measured. Here, we will report estimates of nutrient loads transported in receding floodwaters during tidal flooding associated with perigean spring tides in 2017, 2018, and 2019. During each of the three years, at the highest point of the tide trained, citizen scientists were deployed to areas known to routinely flood in the Lafayette River watershed, a sub-tributary of the lower Chesapeake Bay, located in Norfolk, Virginia (USA). More than 100 samples were collected during each year as the flood waters retreated. Particulate carbon and nitrogen, total dissolved nitrogen, ammonium, nitrite, nitrate, urea, and phosphate were analyzed using standard colorimetric methods. Additionally, samples were analyzed for Enterococcus abundance each year. Results suggest that dissolved inorganic nitrogen loading during a single tidal flooding event exceeds the total annual load allocated for runoff in this sub-estuary.  Because tidal flooding is projected to increase in the future as sea level continues to rise, further research should proceed to better constraint the amounts and characteristics of loadings associated to tidal flooding events. Furthermore, these results suggest that managers should consider nutrient inputs via coastal flooding when setting restoration goals and targets.
Comparing inter-annual variabilities in three regional single model initial-condition large ensembles (SMILE) over Europe
Authors: von Trentini Fabian , Aalbers Emma E. , Fischer Erich M. , Ludwig Ralf
Published: March 2020

Single model large ensembles are widely used model experiments to estimate internal climate variability (here: inter-annual variability). The underlying assumption is that the internal variability of the chosen model is a good approximation of the observed natural variability. In this study, for the first time over Europe, we test this assumption based on the comparison of three regional climate model large ensembles (16 members of an EC-EARTH-RACMO ensemble, 21 members of a CESM-CCLM ensemble, 50 members of a CanESM-CRCM ensemble) for four European domains (British Isles, France, Mid-Europe, Alps). Simulated inter-annual variability is evaluated against E-OBS and the inter-annual variability and its future change are compared across the ensembles. Analyses comprise seasonal temperature and precipitation, as well as indicators for dry periods and heat waves. Results show a large consistency of all three ensembles with E-OBS data for most indicators and regions, validating the abilities of these ensembles to represent natural variability on the annual scale. EC-EARTH-RACMO shows the highest inter-annual variability for winter temperature and precipitation, whereas CESM-CCLM shows the highest variability for summer temperature and precipitation, as well as for heatwaves and dry periods. Despite these model differences, the sign of the future changes in internal variability is largely the same in all models: for summer temperature, summer precipitation and the number of heat waves, the internal variability increases, while it decreases for winter temperature. While dry periods reveal a tendency to increase in variability, the changes of winter precipitation remain less conclusive. The overall consistency across single model large ensembles and observations strengthens the concept of large ensembles, and underlines their great potential for understanding and quantifying internal climate variability and its role in climate change dynamics.